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                    11\   11\                     11\             11\   11\            11\                                       11\
                  1111 |  \__|                    11 |            111\  11 |           11 |                                      11 |
                  \_11 |  11\ 1111111\   1111111\ 1111111\        1111\ 11 | 111111\ 111111\   11\  11\  11\  111111\   111111\  11 |  11\
                    11 |  11 |11  __11\ 11  _____|11  __11\       11 11\11 |11  __11\\_11  _|  11 | 11 | 11 |11  __11\ 11  __11\ 11 | 11  |
                    11 |  11 |11 |  11 |11 /      11 |  11 |      11 \1111 |11111111 | 11 |    11 | 11 | 11 |11 /  11 |11 |  \__|111111  /
                    11 |  11 |11 |  11 |11 |      11 |  11 |      11 |\111 |11   ____| 11 |11\ 11 | 11 | 11 |11 |  11 |11 |      11  _11<
                  111111\ 11 |11 |  11 |\1111111\ 11 |  11 |      11 | \11 |\1111111\  \1111  |\11111\1111  |\111111  |11 |      11 | \11\
                  \______|\__|\__|  \__| \_______|\__|  \__|      \__|  \__| \_______|  \____/  \_____\____/  \______/ \__|      \__|  \__|



                               111111\                                                               11\     11\
                              11  __11\                                                              11 |    \__|
                              11 /  11 | 111111\   111111\   111111\   111111\   111111\   111111\ 111111\   11\  111111\  1111111\
                              11111111 |11  __11\ 11  __11\ 11  __11\ 11  __11\ 11  __11\  \____11\\_11  _|  11 |11  __11\ 11  __11\
                              11  __11 |11 /  11 |11 /  11 |11 |  \__|11111111 |11 /  11 | 1111111 | 11 |    11 |11 /  11 |11 |  11 |
                              11 |  11 |11 |  11 |11 |  11 |11 |      11   ____|11 |  11 |11  __11 | 11 |11\ 11 |11 |  11 |11 |  11 |
                              11 |  11 |\1111111 |\1111111 |11 |      \1111111\ \1111111 |\1111111 | \1111  |11 |\111111  |11 |  11 |
                              \__|  \__| \____11 | \____11 |\__|       \_______| \____11 | \_______|  \____/ \__| \______/ \__|  \__|
                                        11\   11 |11\   11 |                    11\   11 |
                                        \111111  |\111111  |                    \111111  |
                                         \______/  \______/                      \______/
                                                1111111\                        11\
                                                11  __11\                       11 |
                                                11 |  11 | 111111\  11\   11\ 111111\    111111\   111111\
                                                1111111  |11  __11\ 11 |  11 |\_11  _|  11  __11\ 11  __11\
                                                11  __11< 11 /  11 |11 |  11 |  11 |    11111111 |11 |  \__|
                                                11 |  11 |11 |  11 |11 |  11 |  11 |11\ 11   ____|11 |
                                                11 |  11 |\111111  |\111111  |  \1111  |\1111111\ 11 |
                                                \__|  \__| \______/  \______/    \____/  \_______|\__|
*/

// File @openzeppelin/contracts/utils/[email protected]

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}


// File @openzeppelin/contracts/access/[email protected]


pragma solidity ^0.7.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}


// File @openzeppelin/contracts/token/ERC20/[email protected]


pragma solidity ^0.7.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


// File @openzeppelin/contracts/math/[email protected]


pragma solidity ^0.7.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}


// File @openzeppelin/contracts/utils/[email protected]


pragma solidity ^0.7.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}


// File @openzeppelin/contracts/token/ERC20/[email protected]


pragma solidity ^0.7.0;



/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}


// File contracts/helpers/EthReceiver.sol


pragma solidity ^0.7.6;

/// @title Base contract with common payable logics
abstract contract EthReceiver {
    receive() external payable {
        // solhint-disable-next-line avoid-tx-origin
        require(msg.sender != tx.origin, "ETH deposit rejected");
    }
}


// File @openzeppelin/contracts/drafts/[email protected]


pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over `owner`'s tokens,
     * given `owner`'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(address owner, address spender, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for `permit`, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}


// File contracts/helpers/RevertReasonParser.sol


pragma solidity ^0.7.6;

/// @title Library that allows to parse unsuccessful arbitrary calls revert reasons.
/// See https://solidity.readthedocs.io/en/latest/control-structures.html#revert for details.
/// Note that we assume revert reason being abi-encoded as Error(string) so it may fail to parse reason
/// if structured reverts appear in the future.
///
/// All unsuccessful parsings get encoded as Unknown(data) string
library RevertReasonParser {
    bytes4 constant private _PANIC_SELECTOR = bytes4(keccak256("Panic(uint256)"));
    bytes4 constant private _ERROR_SELECTOR = bytes4(keccak256("Error(string)"));

    function parse(bytes memory data, string memory prefix) internal pure returns (string memory) {
        if (data.length >= 4) {
            bytes4 selector;
            assembly {  // solhint-disable-line no-inline-assembly
                selector := mload(add(data, 0x20))
            }

            // 68 = 4-byte selector + 32 bytes offset + 32 bytes length
            if (selector == _ERROR_SELECTOR && data.length >= 68) {
                uint256 offset;
                bytes memory reason;
                // solhint-disable no-inline-assembly
                assembly {
                    // 36 = 32 bytes data length + 4-byte selector
                    offset := mload(add(data, 36))
                    reason := add(data, add(36, offset))
                }
                /*
                    revert reason is padded up to 32 bytes with ABI encoder: Error(string)
                    also sometimes there is extra 32 bytes of zeros padded in the end:
                    https://github.com/ethereum/solidity/issues/10170
                    because of that we can't check for equality and instead check
                    that offset + string length + extra 36 bytes is less than overall data length
                */
                require(data.length >= 36 + offset + reason.length, "Invalid revert reason");
                return string(abi.encodePacked(prefix, "Error(", reason, ")"));
            }
            // 36 = 4-byte selector + 32 bytes integer
            else if (selector == _PANIC_SELECTOR && data.length == 36) {
                uint256 code;
                // solhint-disable no-inline-assembly
                assembly {
                    // 36 = 32 bytes data length + 4-byte selector
                    code := mload(add(data, 36))
                }
                return string(abi.encodePacked(prefix, "Panic(", _toHex(code), ")"));
            }
        }

        return string(abi.encodePacked(prefix, "Unknown(", _toHex(data), ")"));
    }

    function _toHex(uint256 value) private pure returns(string memory) {
        return _toHex(abi.encodePacked(value));
    }

    function _toHex(bytes memory data) private pure returns(string memory) {
        bytes16 alphabet = 0x30313233343536373839616263646566;
        bytes memory str = new bytes(2 + data.length * 2);
        str[0] = "0";
        str[1] = "x";
        for (uint256 i = 0; i < data.length; i++) {
            str[2 * i + 2] = alphabet[uint8(data[i] >> 4)];
            str[2 * i + 3] = alphabet[uint8(data[i] & 0x0f)];
        }
        return string(str);
    }
}


// File contracts/interfaces/IDaiLikePermit.sol


pragma solidity ^0.7.6;

/// @title Interface for DAI-style permits
interface IDaiLikePermit {
    function permit(address holder, address spender, uint256 nonce, uint256 expiry, bool allowed, uint8 v, bytes32 r, bytes32 s) external;
}


// File contracts/helpers/Permitable.sol


pragma solidity ^0.7.6;



/// @title Base contract with common permit handling logics
contract Permitable {
    function _permit(address token, bytes calldata permit) internal {
        if (permit.length > 0) {
            bool success;
            bytes memory result;
            if (permit.length == 32 * 7) {
                // solhint-disable-next-line avoid-low-level-calls
                (success, result) = token.call(abi.encodePacked(IERC20Permit.permit.selector, permit));
            } else if (permit.length == 32 * 8) {
                // solhint-disable-next-line avoid-low-level-calls
                (success, result) = token.call(abi.encodePacked(IDaiLikePermit.permit.selector, permit));
            } else {
                revert("Wrong permit length");
            }
            if (!success) {
                revert(RevertReasonParser.parse(result, "Permit failed: "));
            }
        }
    }
}


// File contracts/helpers/UniERC20.sol


pragma solidity ^0.7.6;




library UniERC20 {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 private constant _ETH_ADDRESS = IERC20(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);
    IERC20 private constant _ZERO_ADDRESS = IERC20(0);

    function isETH(IERC20 token) internal pure returns (bool) {
        return (token == _ZERO_ADDRESS || token == _ETH_ADDRESS);
    }

    function uniBalanceOf(IERC20 token, address account) internal view returns (uint256) {
        if (isETH(token)) {
            return account.balance;
        } else {
            return token.balanceOf(account);
        }
    }

    function uniTransfer(IERC20 token, address payable to, uint256 amount) internal {
        if (amount > 0) {
            if (isETH(token)) {
                to.transfer(amount);
            } else {
                token.safeTransfer(to, amount);
            }
        }
    }

    function uniApprove(IERC20 token, address to, uint256 amount) internal {
        require(!isETH(token), "Approve called on ETH");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(abi.encodeWithSelector(token.approve.selector, to, amount));

        if (!success || (returndata.length > 0 && !abi.decode(returndata, (bool)))) {
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, to, 0));
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, to, amount));
        }
    }

    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory result) = address(token).call(data);
        if (!success) {
            revert(RevertReasonParser.parse(result, "Low-level call failed: "));
        }

        if (result.length > 0) { // Return data is optional
            require(abi.decode(result, (bool)), "ERC20 operation did not succeed");
        }
    }
}


// File contracts/interfaces/IAggregationExecutor.sol


pragma solidity ^0.7.6;

/// @title Interface for making arbitrary calls during swap
interface IAggregationExecutor {
    /// @notice Make calls on `msgSender` with specified data
    function callBytes(address msgSender, bytes calldata data) external payable;  // 0x2636f7f8
}


// File @openzeppelin/contracts/drafts/[email protected]


pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
 *
 * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
 * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
 * they need in their contracts using a combination of `abi.encode` and `keccak256`.
 *
 * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
 * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
 * ({_hashTypedDataV4}).
 *
 * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
 * the chain id to protect against replay attacks on an eventual fork of the chain.
 *
 * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
 * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
 *
 * _Available since v3.4._
 */
abstract contract EIP712 {
    /* solhint-disable var-name-mixedcase */
    // Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
    // invalidate the cached domain separator if the chain id changes.
    bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
    uint256 private immutable _CACHED_CHAIN_ID;

    bytes32 private immutable _HASHED_NAME;
    bytes32 private immutable _HASHED_VERSION;
    bytes32 private immutable _TYPE_HASH;
    /* solhint-enable var-name-mixedcase */

    /**
     * @dev Initializes the domain separator and parameter caches.
     *
     * The meaning of `name` and `version` is specified in
     * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
     *
     * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
     * - `version`: the current major version of the signing domain.
     *
     * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
     * contract upgrade].
     */
    constructor(string memory name, string memory version) {
        bytes32 hashedName = keccak256(bytes(name));
        bytes32 hashedVersion = keccak256(bytes(version));
        bytes32 typeHash = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
        _HASHED_NAME = hashedName;
        _HASHED_VERSION = hashedVersion;
        _CACHED_CHAIN_ID = _getChainId();
        _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
        _TYPE_HASH = typeHash;
    }

    /**
     * @dev Returns the domain separator for the current chain.
     */
    function _domainSeparatorV4() internal view virtual returns (bytes32) {
        if (_getChainId() == _CACHED_CHAIN_ID) {
            return _CACHED_DOMAIN_SEPARATOR;
        } else {
            return _buildDomainSeparator(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION);
        }
    }

    function _buildDomainSeparator(bytes32 typeHash, bytes32 name, bytes32 version) private view returns (bytes32) {
        return keccak256(
            abi.encode(
                typeHash,
                name,
                version,
                _getChainId(),
                address(this)
            )
        );
    }

    /**
     * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
     * function returns the hash of the fully encoded EIP712 message for this domain.
     *
     * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
     *
     * ```solidity
     * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
     *     keccak256("Mail(address to,string contents)"),
     *     mailTo,
     *     keccak256(bytes(mailContents))
     * )));
     * address signer = ECDSA.recover(digest, signature);
     * ```
     */
    function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", _domainSeparatorV4(), structHash));
    }

    function _getChainId() private view returns (uint256 chainId) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        // solhint-disable-next-line no-inline-assembly
        assembly {
            chainId := chainid()
        }
    }
}


// File contracts/helpers/ECDSA.sol


pragma solidity ^0.7.6;

/**
 * @dev Simplified copy of OpenZeppelin ECDSA library downgraded to 0.7.6
 * https://github.com/OpenZeppelin/openzeppelin-contracts/blob/541e82144f691aa171c53ba8c3b32ef7f05b99a5/contracts/utils/cryptography/ECDSA.sol
 *
 * Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature` or error string. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     *
     * Documentation for signature generation:
     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
     *
     * _Available since v4.3._
     */
    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        // Check the signature length
        // - case 65: r,s,v signature (standard)
        // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
        if (signature.length == 65) {
            bytes32 r;
            bytes32 s;
            uint8 v;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            assembly {  // solhint-disable-line no-inline-assembly
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
            return tryRecover(hash, v, r, s);
        } else if (signature.length == 64) {
            bytes32 r;
            bytes32 vs;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            assembly {  // solhint-disable-line no-inline-assembly
                r := mload(add(signature, 0x20))
                vs := mload(add(signature, 0x40))
            }
            return tryRecover(hash, r, vs);
        } else {
            return address(0);
        }
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
     *
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address) {
        bytes32 s;
        uint8 v;
        assembly {  // solhint-disable-line no-inline-assembly
            s := and(vs, 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
            v := add(shr(255, vs), 27)
        }
        return tryRecover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
     * `r` and `s` signature fields separately.
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return address(0);
        }
        if (v != 27 && v != 28) {
            return address(0);
        }

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            return address(0);
        }

        return signer;
    }
}


// File contracts/interfaces/IERC1271.sol


pragma solidity ^0.7.6;

/**
 * @dev Interface of the ERC1271 standard signature validation method for
 * contracts as defined in https://eips.ethereum.org/EIPS/eip-1271[ERC-1271].
 */
interface IERC1271 {
    /**
     * @dev Should return whether the signature provided is valid for the provided data
     * @param hash      Hash of the data to be signed
     * @param signature Signature byte array associated with _data
     */
    function isValidSignature(bytes32 hash, bytes memory signature) external view returns (bytes4 magicValue);
}


// File contracts/interfaces/IWETH.sol


pragma solidity ^0.7.6;

/// @title Interface for WETH tokens
interface IWETH is IERC20 {
    function deposit() external payable;
    function withdraw(uint256 amount) external;
}


// File contracts/LimitOrderProtocolRFQ.sol


pragma solidity ^0.7.6;
pragma abicoder v2;







contract LimitOrderProtocolRFQ is EthReceiver, EIP712("1inch RFQ", "2"), Permitable {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    event OrderFilledRFQ(
        bytes32 orderHash,
        uint256 makingAmount
    );

    struct OrderRFQ {
        // lowest 64 bits is the order id, next 64 bits is the expiration timestamp
        // highest bit is unwrap WETH flag which is set on taker's side
        // [unwrap eth(1 bit) | unused (127 bits) | expiration timestamp(64 bits) | orderId (64 bits)]
        uint256 info;
        IERC20 makerAsset;
        IERC20 takerAsset;
        address maker;
        address allowedSender;  // equals to Zero address on public orders
        uint256 makingAmount;
        uint256 takingAmount;
    }

    bytes32 constant public LIMIT_ORDER_RFQ_TYPEHASH = keccak256(
        "OrderRFQ(uint256 info,address makerAsset,address takerAsset,address maker,address allowedSender,uint256 makingAmount,uint256 takingAmount)"
    );
    uint256 private constant _UNWRAP_WETH_MASK = 1 << 255;

    IWETH private immutable _WETH;  // solhint-disable-line var-name-mixedcase
    mapping(address => mapping(uint256 => uint256)) private _invalidator;

    constructor(address weth) {
        _WETH = IWETH(weth);
    }

    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns(bytes32) {
        return _domainSeparatorV4();
    }

    /// @notice Returns bitmask for double-spend invalidators based on lowest byte of order.info and filled quotes
    /// @return Result Each bit represents whenever corresponding quote was filled
    function invalidatorForOrderRFQ(address maker, uint256 slot) external view returns(uint256) {
        return _invalidator[maker][slot];
    }

    /// @notice Cancels order's quote
    function cancelOrderRFQ(uint256 orderInfo) external {
        _invalidateOrder(msg.sender, orderInfo);
    }

    /// @notice Fills order's quote, fully or partially (whichever is possible)
    /// @param order Order quote to fill
    /// @param signature Signature to confirm quote ownership
    /// @param makingAmount Making amount
    /// @param takingAmount Taking amount
    function fillOrderRFQ(
        OrderRFQ memory order,
        bytes calldata signature,
        uint256 makingAmount,
        uint256 takingAmount
    ) external payable returns(uint256 /* actualMakingAmount */, uint256 /* actualTakingAmount */) {
        return fillOrderRFQTo(order, signature, makingAmount, takingAmount, payable(msg.sender));
    }

    /// @notice Fills Same as `fillOrderRFQ` but calls permit first,
    /// allowing to approve token spending and make a swap in one transaction.
    /// Also allows to specify funds destination instead of `msg.sender`
    /// @param order Order quote to fill
    /// @param signature Signature to confirm quote ownership
    /// @param makingAmount Making amount
    /// @param takingAmount Taking amount
    /// @param target Address that will receive swap funds
    /// @param permit Should consist of abiencoded token address and encoded `IERC20Permit.permit` call.
    /// See tests for examples
    function fillOrderRFQToWithPermit(
        OrderRFQ memory order,
        bytes calldata signature,
        uint256 makingAmount,
        uint256 takingAmount,
        address payable target,
        bytes calldata permit
    ) external returns(uint256 /* actualMakingAmount */, uint256 /* actualTakingAmount */) {
        _permit(address(order.takerAsset), permit);
        return fillOrderRFQTo(order, signature, makingAmount, takingAmount, target);
    }

    /// @notice Same as `fillOrderRFQ` but allows to specify funds destination instead of `msg.sender`
    /// @param order Order quote to fill
    /// @param signature Signature to confirm quote ownership
    /// @param makingAmount Making amount
    /// @param takingAmount Taking amount
    /// @param target Address that will receive swap funds
    function fillOrderRFQTo(
        OrderRFQ memory order,
        bytes calldata signature,
        uint256 makingAmount,
        uint256 takingAmount,
        address payable target
    ) public payable returns(uint256 /* actualMakingAmount */, uint256 /* actualTakingAmount */) {
        address maker = order.maker;
        bool unwrapWETH = (order.info & _UNWRAP_WETH_MASK) > 0;
        order.info = order.info & (_UNWRAP_WETH_MASK - 1);  // zero-out unwrap weth flag as it is taker-only
        {  // Stack too deep
            uint256 info = order.info;
            // Check time expiration
            uint256 expiration = uint128(info) >> 64;
            require(expiration == 0 || block.timestamp <= expiration, "LOP: order expired");  // solhint-disable-line not-rely-on-time
            _invalidateOrder(maker, info);
        }

        {  // stack too deep
            uint256 orderMakingAmount = order.makingAmount;
            uint256 orderTakingAmount = order.takingAmount;
            // Compute partial fill if needed
            if (takingAmount == 0 && makingAmount == 0) {
                // Two zeros means whole order
                makingAmount = orderMakingAmount;
                takingAmount = orderTakingAmount;
            }
            else if (takingAmount == 0) {
                require(makingAmount <= orderMakingAmount, "LOP: making amount exceeded");
                takingAmount = orderTakingAmount.mul(makingAmount).add(orderMakingAmount - 1).div(orderMakingAmount);
            }
            else if (makingAmount == 0) {
                require(takingAmount <= orderTakingAmount, "LOP: taking amount exceeded");
                makingAmount = orderMakingAmount.mul(takingAmount).div(orderTakingAmount);
            }
            else {
                revert("LOP: one of amounts should be 0");
            }
        }

        require(makingAmount > 0 && takingAmount > 0, "LOP: can't swap 0 amount");

        // Validate order
        require(order.allowedSender == address(0) || order.allowedSender == msg.sender, "LOP: private order");
        bytes32 orderHash = _hashTypedDataV4(keccak256(abi.encode(LIMIT_ORDER_RFQ_TYPEHASH, order)));
        _validate(maker, orderHash, signature);

        // Maker => Taker
        if (order.makerAsset == _WETH && unwrapWETH) {
            order.makerAsset.safeTransferFrom(maker, address(this), makingAmount);
            _WETH.withdraw(makingAmount);
            target.transfer(makingAmount);
        } else {
            order.makerAsset.safeTransferFrom(maker, target, makingAmount);
        }
        // Taker => Maker
        if (order.takerAsset == _WETH && msg.value > 0) {
            require(msg.value == takingAmount, "LOP: wrong msg.value");
            _WETH.deposit{ value: takingAmount }();
            _WETH.transfer(maker, takingAmount);
        } else {
            require(msg.value == 0, "LOP: wrong msg.value");
            order.takerAsset.safeTransferFrom(msg.sender, maker, takingAmount);
        }

        emit OrderFilledRFQ(orderHash, makingAmount);
        return (makingAmount, takingAmount);
    }

    function _validate(address signer, bytes32 orderHash, bytes calldata signature) private view {
        if (ECDSA.tryRecover(orderHash, signature) != signer) {
            (bool success, bytes memory result) = signer.staticcall(
                abi.encodeWithSelector(IERC1271.isValidSignature.selector, orderHash, signature)
            );
            require(success && result.length == 32 && abi.decode(result, (bytes4)) == IERC1271.isValidSignature.selector, "LOP: bad signature");
        }
    }

    function _invalidateOrder(address maker, uint256 orderInfo) private {
        uint256 invalidatorSlot = uint64(orderInfo) >> 8;
        uint256 invalidatorBit = 1 << uint8(orderInfo);
        mapping(uint256 => uint256) storage invalidatorStorage = _invalidator[maker];
        uint256 invalidator = invalidatorStorage[invalidatorSlot];
        require(invalidator & invalidatorBit == 0, "LOP: invalidated order");
        invalidatorStorage[invalidatorSlot] = invalidator | invalidatorBit;
    }
}


// File contracts/UnoswapRouter.sol


pragma solidity ^0.7.6;



contract UnoswapRouter is EthReceiver, Permitable {
    uint256 private constant _TRANSFER_FROM_CALL_SELECTOR_32 = 0x23b872dd00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _WETH_DEPOSIT_CALL_SELECTOR_32 = 0xd0e30db000000000000000000000000000000000000000000000000000000000;
    uint256 private constant _WETH_WITHDRAW_CALL_SELECTOR_32 = 0x2e1a7d4d00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _ERC20_TRANSFER_CALL_SELECTOR_32 = 0xa9059cbb00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _ADDRESS_MASK =   0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff;
    uint256 private constant _REVERSE_MASK =   0x8000000000000000000000000000000000000000000000000000000000000000;
    uint256 private constant _WETH_MASK =      0x4000000000000000000000000000000000000000000000000000000000000000;
    uint256 private constant _NUMERATOR_MASK = 0x0000000000000000ffffffff0000000000000000000000000000000000000000;
    /// @dev WETH address is network-specific and needs to be changed before deployment.
    /// It can not be moved to immutable as immutables are not supported in assembly
    uint256 private constant _WETH = 0x000000000000000000000000C02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
    uint256 private constant _UNISWAP_PAIR_RESERVES_CALL_SELECTOR_32 = 0x0902f1ac00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _UNISWAP_PAIR_SWAP_CALL_SELECTOR_32 = 0x022c0d9f00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _DENOMINATOR = 1000000000;
    uint256 private constant _NUMERATOR_OFFSET = 160;

    /// @notice Same as `unoswap` but calls permit first,
    /// allowing to approve token spending and make a swap in one transaction.
    /// @param srcToken Source token
    /// @param amount Amount of source tokens to swap
    /// @param minReturn Minimal allowed returnAmount to make transaction commit
    /// @param pools Pools chain used for swaps. Pools src and dst tokens should match to make swap happen
    /// @param permit Should contain valid permit that can be used in `IERC20Permit.permit` calls.
    /// See tests for examples
    function unoswapWithPermit(
        IERC20 srcToken,
        uint256 amount,
        uint256 minReturn,
        bytes32[] calldata pools,
        bytes calldata permit
    ) external returns(uint256 returnAmount) {
        _permit(address(srcToken), permit);
        return unoswap(srcToken, amount, minReturn, pools);
    }

    /// @notice Performs swap using Uniswap exchange. Wraps and unwraps ETH if required.
    /// Sending non-zero `msg.value` for anything but ETH swaps is prohibited
    /// @param srcToken Source token
    /// @param amount Amount of source tokens to swap
    /// @param minReturn Minimal allowed returnAmount to make transaction commit
    /// @param pools Pools chain used for swaps. Pools src and dst tokens should match to make swap happen
    function unoswap(
        IERC20 srcToken,
        uint256 amount,
        uint256 minReturn,
        // solhint-disable-next-line no-unused-vars
        bytes32[] calldata pools
    ) public payable returns(uint256 returnAmount) {
        assembly {  // solhint-disable-line no-inline-assembly
            function reRevert() {
                returndatacopy(0, 0, returndatasize())
                revert(0, returndatasize())
            }

            function revertWithReason(m, len) {
                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                mstore(0x20, 0x0000002000000000000000000000000000000000000000000000000000000000)
                mstore(0x40, m)
                revert(0, len)
            }

            function swap(emptyPtr, swapAmount, pair, reversed, numerator, dst) -> ret {
                mstore(emptyPtr, _UNISWAP_PAIR_RESERVES_CALL_SELECTOR_32)
                if iszero(staticcall(gas(), pair, emptyPtr, 0x4, emptyPtr, 0x40)) {
                    reRevert()
                }
                if iszero(eq(returndatasize(), 0x60)) {
                    revertWithReason(0x0000001472657365727665732063616c6c206661696c65640000000000000000, 0x59)  // "reserves call failed"
                }

                let reserve0 := mload(emptyPtr)
                let reserve1 := mload(add(emptyPtr, 0x20))
                if reversed {
                    let tmp := reserve0
                    reserve0 := reserve1
                    reserve1 := tmp
                }
                ret := mul(swapAmount, numerator)
                ret := div(mul(ret, reserve1), add(ret, mul(reserve0, _DENOMINATOR)))

                mstore(emptyPtr, _UNISWAP_PAIR_SWAP_CALL_SELECTOR_32)
                switch reversed
                case 0 {
                    mstore(add(emptyPtr, 0x04), 0)
                    mstore(add(emptyPtr, 0x24), ret)
                }
                default {
                    mstore(add(emptyPtr, 0x04), ret)
                    mstore(add(emptyPtr, 0x24), 0)
                }
                mstore(add(emptyPtr, 0x44), dst)
                mstore(add(emptyPtr, 0x64), 0x80)
                mstore(add(emptyPtr, 0x84), 0)
                if iszero(call(gas(), pair, 0, emptyPtr, 0xa4, 0, 0)) {
                    reRevert()
                }
            }

            let emptyPtr := mload(0x40)
            mstore(0x40, add(emptyPtr, 0xc0))

            let poolsOffset := add(calldataload(0x64), 0x4)
            let poolsEndOffset := calldataload(poolsOffset)
            poolsOffset := add(poolsOffset, 0x20)
            poolsEndOffset := add(poolsOffset, mul(0x20, poolsEndOffset))
            let rawPair := calldataload(poolsOffset)
            switch srcToken
            case 0 {
                if iszero(eq(amount, callvalue())) {
                    revertWithReason(0x00000011696e76616c6964206d73672e76616c75650000000000000000000000, 0x55)  // "invalid msg.value"
                }

                mstore(emptyPtr, _WETH_DEPOSIT_CALL_SELECTOR_32)
                if iszero(call(gas(), _WETH, amount, emptyPtr, 0x4, 0, 0)) {
                    reRevert()
                }

                mstore(emptyPtr, _ERC20_TRANSFER_CALL_SELECTOR_32)
                mstore(add(emptyPtr, 0x4), and(rawPair, _ADDRESS_MASK))
                mstore(add(emptyPtr, 0x24), amount)
                if iszero(call(gas(), _WETH, 0, emptyPtr, 0x44, 0, 0)) {
                    reRevert()
                }
            }
            default {
                if callvalue() {
                    revertWithReason(0x00000011696e76616c6964206d73672e76616c75650000000000000000000000, 0x55)  // "invalid msg.value"
                }

                mstore(emptyPtr, _TRANSFER_FROM_CALL_SELECTOR_32)
                mstore(add(emptyPtr, 0x4), caller())
                mstore(add(emptyPtr, 0x24), and(rawPair, _ADDRESS_MASK))
                mstore(add(emptyPtr, 0x44), amount)
                if iszero(call(gas(), srcToken, 0, emptyPtr, 0x64, 0, 0)) {
                    reRevert()
                }
            }

            returnAmount := amount

            for {let i := add(poolsOffset, 0x20)} lt(i, poolsEndOffset) {i := add(i, 0x20)} {
                let nextRawPair := calldataload(i)

                returnAmount := swap(
                    emptyPtr,
                    returnAmount,
                    and(rawPair, _ADDRESS_MASK),
                    and(rawPair, _REVERSE_MASK),
                    shr(_NUMERATOR_OFFSET, and(rawPair, _NUMERATOR_MASK)),
                    and(nextRawPair, _ADDRESS_MASK)
                )

                rawPair := nextRawPair
            }

            switch and(rawPair, _WETH_MASK)
            case 0 {
                returnAmount := swap(
                    emptyPtr,
                    returnAmount,
                    and(rawPair, _ADDRESS_MASK),
                    and(rawPair, _REVERSE_MASK),
                    shr(_NUMERATOR_OFFSET, and(rawPair, _NUMERATOR_MASK)),
                    caller()
                )
            }
            default {
                returnAmount := swap(
                    emptyPtr,
                    returnAmount,
                    and(rawPair, _ADDRESS_MASK),
                    and(rawPair, _REVERSE_MASK),
                    shr(_NUMERATOR_OFFSET, and(rawPair, _NUMERATOR_MASK)),
                    address()
                )

                mstore(emptyPtr, _WETH_WITHDRAW_CALL_SELECTOR_32)
                mstore(add(emptyPtr, 0x04), returnAmount)
                if iszero(call(gas(), _WETH, 0, emptyPtr, 0x24, 0, 0)) {
                    reRevert()
                }

                if iszero(call(gas(), caller(), returnAmount, 0, 0, 0, 0)) {
                    reRevert()
                }
            }

            if lt(returnAmount, minReturn) {
                revertWithReason(0x000000164d696e2072657475726e206e6f742072656163686564000000000000, 0x5a)  // "Min return not reached"
            }
        }
    }
}


// File @openzeppelin/contracts/utils/[email protected]


pragma solidity ^0.7.0;


/**
 * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
 * checks.
 *
 * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
 * easily result in undesired exploitation or bugs, since developers usually
 * assume that overflows raise errors. `SafeCast` restores this intuition by
 * reverting the transaction when such an operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 *
 * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
 * all math on `uint256` and `int256` and then downcasting.
 */
library SafeCast {

    /**
     * @dev Returns the downcasted uint128 from uint256, reverting on
     * overflow (when the input is greater than largest uint128).
     *
     * Counterpart to Solidity's `uint128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     */
    function toUint128(uint256 value) internal pure returns (uint128) {
        require(value < 2**128, "SafeCast: value doesn\'t fit in 128 bits");
        return uint128(value);
    }

    /**
     * @dev Returns the downcasted uint64 from uint256, reverting on
     * overflow (when the input is greater than largest uint64).
     *
     * Counterpart to Solidity's `uint64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     */
    function toUint64(uint256 value) internal pure returns (uint64) {
        require(value < 2**64, "SafeCast: value doesn\'t fit in 64 bits");
        return uint64(value);
    }

    /**
     * @dev Returns the downcasted uint32 from uint256, reverting on
     * overflow (when the input is greater than largest uint32).
     *
     * Counterpart to Solidity's `uint32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     */
    function toUint32(uint256 value) internal pure returns (uint32) {
        require(value < 2**32, "SafeCast: value doesn\'t fit in 32 bits");
        return uint32(value);
    }

    /**
     * @dev Returns the downcasted uint16 from uint256, reverting on
     * overflow (when the input is greater than largest uint16).
     *
     * Counterpart to Solidity's `uint16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     */
    function toUint16(uint256 value) internal pure returns (uint16) {
        require(value < 2**16, "SafeCast: value doesn\'t fit in 16 bits");
        return uint16(value);
    }

    /**
     * @dev Returns the downcasted uint8 from uint256, reverting on
     * overflow (when the input is greater than largest uint8).
     *
     * Counterpart to Solidity's `uint8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     */
    function toUint8(uint256 value) internal pure returns (uint8) {
        require(value < 2**8, "SafeCast: value doesn\'t fit in 8 bits");
        return uint8(value);
    }

    /**
     * @dev Converts a signed int256 into an unsigned uint256.
     *
     * Requirements:
     *
     * - input must be greater than or equal to 0.
     */
    function toUint256(int256 value) internal pure returns (uint256) {
        require(value >= 0, "SafeCast: value must be positive");
        return uint256(value);
    }

    /**
     * @dev Returns the downcasted int128 from int256, reverting on
     * overflow (when the input is less than smallest int128 or
     * greater than largest int128).
     *
     * Counterpart to Solidity's `int128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v3.1._
     */
    function toInt128(int256 value) internal pure returns (int128) {
        require(value >= -2**127 && value < 2**127, "SafeCast: value doesn\'t fit in 128 bits");
        return int128(value);
    }

    /**
     * @dev Returns the downcasted int64 from int256, reverting on
     * overflow (when the input is less than smallest int64 or
     * greater than largest int64).
     *
     * Counterpart to Solidity's `int64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v3.1._
     */
    function toInt64(int256 value) internal pure returns (int64) {
        require(value >= -2**63 && value < 2**63, "SafeCast: value doesn\'t fit in 64 bits");
        return int64(value);
    }

    /**
     * @dev Returns the downcasted int32 from int256, reverting on
     * overflow (when the input is less than smallest int32 or
     * greater than largest int32).
     *
     * Counterpart to Solidity's `int32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v3.1._
     */
    function toInt32(int256 value) internal pure returns (int32) {
        require(value >= -2**31 && value < 2**31, "SafeCast: value doesn\'t fit in 32 bits");
        return int32(value);
    }

    /**
     * @dev Returns the downcasted int16 from int256, reverting on
     * overflow (when the input is less than smallest int16 or
     * greater than largest int16).
     *
     * Counterpart to Solidity's `int16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v3.1._
     */
    function toInt16(int256 value) internal pure returns (int16) {
        require(value >= -2**15 && value < 2**15, "SafeCast: value doesn\'t fit in 16 bits");
        return int16(value);
    }

    /**
     * @dev Returns the downcasted int8 from int256, reverting on
     * overflow (when the input is less than smallest int8 or
     * greater than largest int8).
     *
     * Counterpart to Solidity's `int8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     *
     * _Available since v3.1._
     */
    function toInt8(int256 value) internal pure returns (int8) {
        require(value >= -2**7 && value < 2**7, "SafeCast: value doesn\'t fit in 8 bits");
        return int8(value);
    }

    /**
     * @dev Converts an unsigned uint256 into a signed int256.
     *
     * Requirements:
     *
     * - input must be less than or equal to maxInt256.
     */
    function toInt256(uint256 value) internal pure returns (int256) {
        require(value < 2**255, "SafeCast: value doesn't fit in an int256");
        return int256(value);
    }
}


// File contracts/interfaces/IUniswapV3Pool.sol

pragma solidity ^0.7.6;

interface IUniswapV3Pool {
    /// @notice Swap token0 for token1, or token1 for token0
    /// @dev The caller of this method receives a callback in the form of IUniswapV3SwapCallback#uniswapV3SwapCallback
    /// @param recipient The address to receive the output of the swap
    /// @param zeroForOne The direction of the swap, true for token0 to token1, false for token1 to token0
    /// @param amountSpecified The amount of the swap, which implicitly configures the swap as exact input (positive), or exact output (negative)
    /// @param sqrtPriceLimitX96 The Q64.96 sqrt price limit. If zero for one, the price cannot be less than this
    /// value after the swap. If one for zero, the price cannot be greater than this value after the swap
    /// @param data Any data to be passed through to the callback
    /// @return amount0 The delta of the balance of token0 of the pool, exact when negative, minimum when positive
    /// @return amount1 The delta of the balance of token1 of the pool, exact when negative, minimum when positive
    function swap(
        address recipient,
        bool zeroForOne,
        int256 amountSpecified,
        uint160 sqrtPriceLimitX96,
        bytes calldata data
    ) external returns (int256 amount0, int256 amount1);

    /// @notice The first of the two tokens of the pool, sorted by address
    /// @return The token contract address
    function token0() external view returns (address);

    /// @notice The second of the two tokens of the pool, sorted by address
    /// @return The token contract address
    function token1() external view returns (address);

    /// @notice The pool's fee in hundredths of a bip, i.e. 1e-6
    /// @return The fee
    function fee() external view returns (uint24);
}


// File contracts/interfaces/IUniswapV3SwapCallback.sol

pragma solidity ^0.7.6;

/// @title Callback for IUniswapV3PoolActions#swap
/// @notice Any contract that calls IUniswapV3PoolActions#swap must implement this interface
interface IUniswapV3SwapCallback {
    /// @notice Called to `msg.sender` after executing a swap via IUniswapV3Pool#swap.
    /// @dev In the implementation you must pay the pool tokens owed for the swap.
    /// The caller of this method must be checked to be a UniswapV3Pool deployed by the canonical UniswapV3Factory.
    /// amount0Delta and amount1Delta can both be 0 if no tokens were swapped.
    /// @param amount0Delta The amount of token0 that was sent (negative) or must be received (positive) by the pool by
    /// the end of the swap. If positive, the callback must send that amount of token0 to the pool.
    /// @param amount1Delta The amount of token1 that was sent (negative) or must be received (positive) by the pool by
    /// the end of the swap. If positive, the callback must send that amount of token1 to the pool.
    /// @param data Any data passed through by the caller via the IUniswapV3PoolActions#swap call
    function uniswapV3SwapCallback(
        int256 amount0Delta,
        int256 amount1Delta,
        bytes calldata data
    ) external;
}


// File contracts/UnoswapV3Router.sol


pragma solidity ^0.7.6;









contract UnoswapV3Router is EthReceiver, Permitable, IUniswapV3SwapCallback {
    using Address for address payable;
    using SafeERC20 for IERC20;
    using SafeMath for uint256;

    uint256 private constant _ONE_FOR_ZERO_MASK = 1 << 255;
    uint256 private constant _WETH_WRAP_MASK = 1 << 254;
    uint256 private constant _WETH_UNWRAP_MASK = 1 << 253;
    bytes32 private constant _POOL_INIT_CODE_HASH = 0xe34f199b19b2b4f47f68442619d555527d244f78a3297ea89325f843f87b8b54;
    bytes32 private constant _FF_FACTORY = 0xff1F98431c8aD98523631AE4a59f267346ea31F9840000000000000000000000;
    bytes32 private constant _SELECTORS = 0x0dfe1681d21220a7ddca3f430000000000000000000000000000000000000000;
    uint256 private constant _ADDRESS_MASK =   0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff;
    /// @dev The minimum value that can be returned from #getSqrtRatioAtTick. Equivalent to getSqrtRatioAtTick(MIN_TICK)
    uint160 private constant _MIN_SQRT_RATIO = 4295128739 + 1;
    /// @dev The maximum value that can be returned from #getSqrtRatioAtTick. Equivalent to getSqrtRatioAtTick(MAX_TICK)
    uint160 private constant _MAX_SQRT_RATIO = 1461446703485210103287273052203988822378723970342 - 1;
    IWETH private immutable _WETH;  // solhint-disable-line var-name-mixedcase

    constructor(address weth) {
        _WETH = IWETH(weth);
    }

    /// @notice Same as `uniswapV3SwapTo` but calls permit first,
    /// allowing to approve token spending and make a swap in one transaction.
    /// @param recipient Address that will receive swap funds
    /// @param srcToken Source token
    /// @param amount Amount of source tokens to swap
    /// @param minReturn Minimal allowed returnAmount to make transaction commit
    /// @param pools Pools chain used for swaps. Pools src and dst tokens should match to make swap happen
    /// @param permit Should contain valid permit that can be used in `IERC20Permit.permit` calls.
    /// See tests for examples
    function uniswapV3SwapToWithPermit(
        address payable recipient,
        IERC20 srcToken,
        uint256 amount,
        uint256 minReturn,
        uint256[] calldata pools,
        bytes calldata permit
    ) external returns(uint256 returnAmount) {
        _permit(address(srcToken), permit);
        return uniswapV3SwapTo(recipient, amount, minReturn, pools);
    }

    /// @notice Same as `uniswapV3SwapTo` but uses `msg.sender` as recipient
    /// @param amount Amount of source tokens to swap
    /// @param minReturn Minimal allowed returnAmount to make transaction commit
    /// @param pools Pools chain used for swaps. Pools src and dst tokens should match to make swap happen
    function uniswapV3Swap(
        uint256 amount,
        uint256 minReturn,
        uint256[] calldata pools
    ) external payable returns(uint256 returnAmount) {
        return uniswapV3SwapTo(msg.sender, amount, minReturn, pools);
    }

    /// @notice Performs swap using Uniswap V3 exchange. Wraps and unwraps ETH if required.
    /// Sending non-zero `msg.value` for anything but ETH swaps is prohibited
    /// @param recipient Address that will receive swap funds
    /// @param amount Amount of source tokens to swap
    /// @param minReturn Minimal allowed returnAmount to make transaction commit
    /// @param pools Pools chain used for swaps. Pools src and dst tokens should match to make swap happen
    function uniswapV3SwapTo(
        address payable recipient,
        uint256 amount,
        uint256 minReturn,
        uint256[] calldata pools
    ) public payable returns(uint256 returnAmount) {
        uint256 len = pools.length;
        require(len > 0, "UNIV3R: empty pools");
        uint256 lastIndex = len - 1;
        returnAmount = amount;
        bool wrapWeth = pools[0] & _WETH_WRAP_MASK > 0;
        bool unwrapWeth = pools[lastIndex] & _WETH_UNWRAP_MASK > 0;
        if (wrapWeth) {
            require(msg.value == amount, "UNIV3R: wrong msg.value");
            _WETH.deposit{value: amount}();
        } else {
            require(msg.value == 0, "UNIV3R: msg.value should be 0");
        }
        if (len > 1) {
            returnAmount = _makeSwap(address(this), wrapWeth ? address(this) : msg.sender, pools[0], returnAmount);

            for (uint256 i = 1; i < lastIndex; i++) {
                returnAmount = _makeSwap(address(this), address(this), pools[i], returnAmount);
            }
            returnAmount = _makeSwap(unwrapWeth ? address(this) : recipient, address(this), pools[lastIndex], returnAmount);
        } else {
            returnAmount = _makeSwap(unwrapWeth ? address(this) : recipient, wrapWeth ? address(this) : msg.sender, pools[0], returnAmount);
        }

        require(returnAmount >= minReturn, "UNIV3R: min return");

        if (unwrapWeth) {
            _WETH.withdraw(returnAmount);
            recipient.sendValue(returnAmount);
        }
    }

    /// @inheritdoc IUniswapV3SwapCallback
    function uniswapV3SwapCallback(
        int256 amount0Delta,
        int256 amount1Delta,
        bytes calldata /* data */
    ) external override {
        IERC20 token0;
        IERC20 token1;
        bytes32 ffFactoryAddress = _FF_FACTORY;
        bytes32 poolInitCodeHash = _POOL_INIT_CODE_HASH;
        address payer;

        assembly {  // solhint-disable-line no-inline-assembly
            function reRevert() {
                returndatacopy(0, 0, returndatasize())
                revert(0, returndatasize())
            }

            function revertWithReason(m, len) {
                mstore(0x00, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                mstore(0x20, 0x0000002000000000000000000000000000000000000000000000000000000000)
                mstore(0x40, m)
                revert(0, len)
            }

            let emptyPtr := mload(0x40)
            let resultPtr := add(emptyPtr, 0x20)
            mstore(emptyPtr, _SELECTORS)

            if iszero(staticcall(gas(), caller(), emptyPtr, 0x4, resultPtr, 0x20)) {
                reRevert()
            }
            token0 := mload(resultPtr)
            if iszero(staticcall(gas(), caller(), add(emptyPtr, 0x4), 0x4, resultPtr, 0x20)) {
                reRevert()
            }
            token1 := mload(resultPtr)
            if iszero(staticcall(gas(), caller(), add(emptyPtr, 0x8), 0x4, resultPtr, 0x20)) {
                reRevert()
            }
            let fee := mload(resultPtr)

            let p := emptyPtr
            mstore(p, ffFactoryAddress)
            p := add(p, 21)
            // Compute the inner hash in-place
            mstore(p, token0)
            mstore(add(p, 32), token1)
            mstore(add(p, 64), fee)
            mstore(p, keccak256(p, 96))
            p := add(p, 32)
            mstore(p, poolInitCodeHash)
            let pool := and(keccak256(emptyPtr, 85), _ADDRESS_MASK)

            if iszero(eq(pool, caller())) {
                revertWithReason(0x00000010554e495633523a2062616420706f6f6c000000000000000000000000, 0x54)  // UNIV3R: bad pool
            }

            calldatacopy(emptyPtr, 0x84, 0x20)
            payer := mload(emptyPtr)
        }

        if (amount0Delta > 0) {
            if (payer == address(this)) {
                token0.safeTransfer(msg.sender, uint256(amount0Delta));
            } else {
                token0.safeTransferFrom(payer, msg.sender, uint256(amount0Delta));
            }
        }
        if (amount1Delta > 0) {
            if (payer == address(this)) {
                token1.safeTransfer(msg.sender, uint256(amount1Delta));
            } else {
                token1.safeTransferFrom(payer, msg.sender, uint256(amount1Delta));
            }
        }
    }

    function _makeSwap(address recipient, address payer, uint256 pool, uint256 amount) private returns (uint256) {
        bool zeroForOne = pool & _ONE_FOR_ZERO_MASK == 0;
        if (zeroForOne) {
            (, int256 amount1) = IUniswapV3Pool(pool).swap(
                recipient,
                zeroForOne,
                SafeCast.toInt256(amount),
                _MIN_SQRT_RATIO,
                abi.encode(payer)
            );
            return SafeCast.toUint256(-amount1);
        } else {
            (int256 amount0,) = IUniswapV3Pool(pool).swap(
                recipient,
                zeroForOne,
                SafeCast.toInt256(amount),
                _MAX_SQRT_RATIO,
                abi.encode(payer)
            );
            return SafeCast.toUint256(-amount0);
        }
    }
}


// File contracts/interfaces/IClipperExchangeInterface.sol


pragma solidity ^0.7.6;

/// @title Clipper interface subset used in swaps
interface IClipperExchangeInterface {
    function sellTokenForToken(IERC20 inputToken, IERC20 outputToken, address recipient, uint256 minBuyAmount, bytes calldata auxiliaryData) external returns (uint256 boughtAmount);
    function sellEthForToken(IERC20 outputToken, address recipient, uint256 minBuyAmount, bytes calldata auxiliaryData) external payable returns (uint256 boughtAmount);
    function sellTokenForEth(IERC20 inputToken, address payable recipient, uint256 minBuyAmount, bytes calldata auxiliaryData) external returns (uint256 boughtAmount);
    function theExchange() external returns (address payable);
}


// File contracts/ClipperRouter.sol


pragma solidity ^0.7.6;






/// @title Clipper router that allows to use `ClipperExchangeInterface` for swaps
contract ClipperRouter is EthReceiver, Permitable {
    using SafeERC20 for IERC20;

    IWETH private immutable _WETH;  // solhint-disable-line var-name-mixedcase
    IERC20 private constant _ETH = IERC20(address(0));
    bytes private constant _INCH_TAG = "1INCH";
    IClipperExchangeInterface private immutable _clipperExchange;
    address payable private immutable _clipperPool;

    constructor(
        address weth,
        IClipperExchangeInterface clipperExchange
    ) {
        _clipperExchange = clipperExchange;
        _clipperPool = clipperExchange.theExchange();
        _WETH = IWETH(weth);
    }

    /// @notice Same as `clipperSwapTo` but calls permit first,
    /// allowing to approve token spending and make a swap in one transaction.
    /// @param recipient Address that will receive swap funds
    /// @param srcToken Source token
    /// @param dstToken Destination token
    /// @param amount Amount of source tokens to swap
    /// @param minReturn Minimal allowed returnAmount to make transaction commit
    /// @param permit Should contain valid permit that can be used in `IERC20Permit.permit` calls.
    /// See tests for examples
    function clipperSwapToWithPermit(
        address payable recipient,
        IERC20 srcToken,
        IERC20 dstToken,
        uint256 amount,
        uint256 minReturn,
        bytes calldata permit
    ) external returns(uint256 returnAmount) {
        _permit(address(srcToken), permit);
        return clipperSwapTo(recipient, srcToken, dstToken, amount, minReturn);
    }

    /// @notice Same as `clipperSwapTo` but uses `msg.sender` as recipient
    /// @param srcToken Source token
    /// @param dstToken Destination token
    /// @param amount Amount of source tokens to swap
    /// @param minReturn Minimal allowed returnAmount to make transaction commit
    function clipperSwap(
        IERC20 srcToken,
        IERC20 dstToken,
        uint256 amount,
        uint256 minReturn
    ) external payable returns(uint256 returnAmount) {
        return clipperSwapTo(msg.sender, srcToken, dstToken, amount, minReturn);
    }

    /// @notice Performs swap using Clipper exchange. Wraps and unwraps ETH if required.
    /// Sending non-zero `msg.value` for anything but ETH swaps is prohibited
    /// @param recipient Address that will receive swap funds
    /// @param srcToken Source token
    /// @param dstToken Destination token
    /// @param amount Amount of source tokens to swap
    /// @param minReturn Minimal allowed returnAmount to make transaction commit
    function clipperSwapTo(
        address payable recipient,
        IERC20 srcToken,
        IERC20 dstToken,
        uint256 amount,
        uint256 minReturn
    ) public payable returns(uint256 returnAmount) {
        bool srcETH;
        if (srcToken == _WETH) {
            require(msg.value == 0, "CL1IN: msg.value should be 0");
            _WETH.transferFrom(msg.sender, address(this), amount);
            _WETH.withdraw(amount);
            srcETH = true;
        }
        else if (srcToken == _ETH) {
            require(msg.value == amount, "CL1IN: wrong msg.value");
            srcETH = true;
        }
        else {
            require(msg.value == 0, "CL1IN: msg.value should be 0");
            srcToken.safeTransferFrom(msg.sender, _clipperPool, amount);
        }

        if (srcETH) {
            _clipperPool.transfer(amount);
            returnAmount = _clipperExchange.sellEthForToken(dstToken, recipient, minReturn, _INCH_TAG);
        } else if (dstToken == _WETH) {
            returnAmount = _clipperExchange.sellTokenForEth(srcToken, address(this), minReturn, _INCH_TAG);
            _WETH.deposit{ value: returnAmount }();
            _WETH.transfer(recipient, returnAmount);
        } else if (dstToken == _ETH) {
            returnAmount = _clipperExchange.sellTokenForEth(srcToken, recipient, minReturn, _INCH_TAG);
        } else {
            returnAmount = _clipperExchange.sellTokenForToken(srcToken, dstToken, recipient, minReturn, _INCH_TAG);
        }
    }
}


// File contracts/AggregationRouterV4.sol


pragma solidity ^0.7.6;



contract AggregationRouterV4 is Ownable, EthReceiver, Permitable, UnoswapRouter, UnoswapV3Router, LimitOrderProtocolRFQ, ClipperRouter {
    using SafeMath for uint256;
    using UniERC20 for IERC20;
    using SafeERC20 for IERC20;

    uint256 private constant _PARTIAL_FILL = 1 << 0;
    uint256 private constant _REQUIRES_EXTRA_ETH = 1 << 1;

    struct SwapDescription {
        IERC20 srcToken;
        IERC20 dstToken;
        address payable srcReceiver;
        address payable dstReceiver;
        uint256 amount;
        uint256 minReturnAmount;
        uint256 flags;
        bytes permit;
    }

    constructor(address weth, IClipperExchangeInterface _clipperExchange)
        UnoswapV3Router(weth)
        LimitOrderProtocolRFQ(weth)
        ClipperRouter(weth, _clipperExchange)
    {}  // solhint-disable-line no-empty-blocks

    /// @notice Performs a swap, delegating all calls encoded in `data` to `caller`. See tests for usage examples
    /// @param caller Aggregation executor that executes calls described in `data`
    /// @param desc Swap description
    /// @param data Encoded calls that `caller` should execute in between of swaps
    /// @return returnAmount Resulting token amount
    /// @return spentAmount Source token amount
    /// @return gasLeft Gas left
    function swap(
        IAggregationExecutor caller,
        SwapDescription calldata desc,
        bytes calldata data
    )
        external
        payable
        returns (
            uint256 returnAmount,
            uint256 spentAmount,
            uint256 gasLeft
        )
    {
        require(desc.minReturnAmount > 0, "Min return should not be 0");
        require(data.length > 0, "data should not be empty");

        uint256 flags = desc.flags;
        IERC20 srcToken = desc.srcToken;
        IERC20 dstToken = desc.dstToken;

        bool srcETH = srcToken.isETH();
        if (flags & _REQUIRES_EXTRA_ETH != 0) {
            require(msg.value > (srcETH ? desc.amount : 0), "Invalid msg.value");
        } else {
            require(msg.value == (srcETH ? desc.amount : 0), "Invalid msg.value");
        }

        if (!srcETH) {
            _permit(address(srcToken), desc.permit);
            srcToken.safeTransferFrom(msg.sender, desc.srcReceiver, desc.amount);
        }

        {
            bytes memory callData = abi.encodePacked(caller.callBytes.selector, bytes12(0), msg.sender, data);
            // solhint-disable-next-line avoid-low-level-calls
            (bool success, bytes memory result) = address(caller).call{value: msg.value}(callData);
            if (!success) {
                revert(RevertReasonParser.parse(result, "callBytes failed: "));
            }
        }

        spentAmount = desc.amount;
        returnAmount = dstToken.uniBalanceOf(address(this));

        if (flags & _PARTIAL_FILL != 0) {
            uint256 unspentAmount = srcToken.uniBalanceOf(address(this));
            if (unspentAmount > 0) {
                spentAmount = spentAmount.sub(unspentAmount);
                srcToken.uniTransfer(msg.sender, unspentAmount);
            }
            require(returnAmount.mul(desc.amount) >= desc.minReturnAmount.mul(spentAmount), "Return amount is not enough");
        } else {
            require(returnAmount >= desc.minReturnAmount, "Return amount is not enough");
        }

        address payable dstReceiver = (desc.dstReceiver == address(0)) ? msg.sender : desc.dstReceiver;
        dstToken.uniTransfer(dstReceiver, returnAmount);

        gasLeft = gasleft();
    }

    function rescueFunds(IERC20 token, uint256 amount) external onlyOwner {
        token.uniTransfer(msg.sender, amount);
    }

    function destroy() external onlyOwner {
        selfdestruct(msg.sender);
    }
}

// File: contracts/uniswapv2/interfaces/IUniswapV2Factory.sol

pragma solidity >=0.5.0;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);
    function migrator() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
    function setMigrator(address) external;
}

// File: contracts/uniswapv2/libraries/SafeMath.sol

pragma solidity =0.6.12;

// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)

library SafeMathUniswap {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}

// File: contracts/uniswapv2/UniswapV2ERC20.sol

pragma solidity =0.6.12;


contract UniswapV2ERC20 {
    using SafeMathUniswap for uint;

    string public constant name = 'SushiSwap LP Token';
    string public constant symbol = 'SLP';
    uint8 public constant decimals = 18;
    uint  public totalSupply;
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;

    bytes32 public DOMAIN_SEPARATOR;
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    mapping(address => uint) public nonces;

    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    constructor() public {
        uint chainId;
        assembly {
            chainId := chainid()
        }
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                keccak256(bytes(name)),
                keccak256(bytes('1')),
                chainId,
                address(this)
            )
        );
    }

    function _mint(address to, uint value) internal {
        totalSupply = totalSupply.add(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(address(0), to, value);
    }

    function _burn(address from, uint value) internal {
        balanceOf[from] = balanceOf[from].sub(value);
        totalSupply = totalSupply.sub(value);
        emit Transfer(from, address(0), value);
    }

    function _approve(address owner, address spender, uint value) private {
        allowance[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _transfer(address from, address to, uint value) private {
        balanceOf[from] = balanceOf[from].sub(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(from, to, value);
    }

    function approve(address spender, uint value) external returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transfer(address to, uint value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(address from, address to, uint value) external returns (bool) {
        if (allowance[from][msg.sender] != uint(-1)) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
        }
        _transfer(from, to, value);
        return true;
    }

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
        require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
        bytes32 digest = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
        _approve(owner, spender, value);
    }
}

// File: contracts/uniswapv2/libraries/Math.sol

pragma solidity =0.6.12;

// a library for performing various math operations

library Math {
    function min(uint x, uint y) internal pure returns (uint z) {
        z = x < y ? x : y;
    }

    // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
    function sqrt(uint y) internal pure returns (uint z) {
        if (y > 3) {
            z = y;
            uint x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }
}

// File: contracts/uniswapv2/libraries/UQ112x112.sol

pragma solidity =0.6.12;

// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))

// range: [0, 2**112 - 1]
// resolution: 1 / 2**112

library UQ112x112 {
    uint224 constant Q112 = 2**112;

    // encode a uint112 as a UQ112x112
    function encode(uint112 y) internal pure returns (uint224 z) {
        z = uint224(y) * Q112; // never overflows
    }

    // divide a UQ112x112 by a uint112, returning a UQ112x112
    function uqdiv(uint224 x, uint112 y) internal pure returns (uint224 z) {
        z = x / uint224(y);
    }
}

// File: contracts/uniswapv2/interfaces/IERC20.sol

pragma solidity >=0.5.0;

interface IERC20Uniswap {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

// File: contracts/uniswapv2/interfaces/IUniswapV2Callee.sol

pragma solidity >=0.5.0;

interface IUniswapV2Callee {
    function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
}

// File: contracts/uniswapv2/UniswapV2Pair.sol

pragma solidity =0.6.12;








interface IMigrator {
    // Return the desired amount of liquidity token that the migrator wants.
    function desiredLiquidity() external view returns (uint256);
}

contract UniswapV2Pair is UniswapV2ERC20 {
    using SafeMathUniswap  for uint;
    using UQ112x112 for uint224;

    uint public constant MINIMUM_LIQUIDITY = 10**3;
    bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));

    address public factory;
    address public token0;
    address public token1;

    uint112 private reserve0;           // uses single storage slot, accessible via getReserves
    uint112 private reserve1;           // uses single storage slot, accessible via getReserves
    uint32  private blockTimestampLast; // uses single storage slot, accessible via getReserves

    uint public price0CumulativeLast;
    uint public price1CumulativeLast;
    uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event

    uint private unlocked = 1;
    modifier lock() {
        require(unlocked == 1, 'UniswapV2: LOCKED');
        unlocked = 0;
        _;
        unlocked = 1;
    }

    function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
        _reserve0 = reserve0;
        _reserve1 = reserve1;
        _blockTimestampLast = blockTimestampLast;
    }

    function _safeTransfer(address token, address to, uint value) private {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'UniswapV2: TRANSFER_FAILED');
    }

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    constructor() public {
        factory = msg.sender;
    }

    // called once by the factory at time of deployment
    function initialize(address _token0, address _token1) external {
        require(msg.sender == factory, 'UniswapV2: FORBIDDEN'); // sufficient check
        token0 = _token0;
        token1 = _token1;
    }

    // update reserves and, on the first call per block, price accumulators
    function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
        require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'UniswapV2: OVERFLOW');
        uint32 blockTimestamp = uint32(block.timestamp % 2**32);
        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
        if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
            // * never overflows, and + overflow is desired
            price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
            price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
        }
        reserve0 = uint112(balance0);
        reserve1 = uint112(balance1);
        blockTimestampLast = blockTimestamp;
        emit Sync(reserve0, reserve1);
    }

    // if fee is on, mint liquidity equivalent to 1/6th of the growth in sqrt(k)
    function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
        address feeTo = IUniswapV2Factory(factory).feeTo();
        feeOn = feeTo != address(0);
        uint _kLast = kLast; // gas savings
        if (feeOn) {
            if (_kLast != 0) {
                uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
                uint rootKLast = Math.sqrt(_kLast);
                if (rootK > rootKLast) {
                    uint numerator = totalSupply.mul(rootK.sub(rootKLast));
                    uint denominator = rootK.mul(5).add(rootKLast);
                    uint liquidity = numerator / denominator;
                    if (liquidity > 0) _mint(feeTo, liquidity);
                }
            }
        } else if (_kLast != 0) {
            kLast = 0;
        }
    }

    // this low-level function should be called from a contract which performs important safety checks
    function mint(address to) external lock returns (uint liquidity) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        uint balance0 = IERC20Uniswap(token0).balanceOf(address(this));
        uint balance1 = IERC20Uniswap(token1).balanceOf(address(this));
        uint amount0 = balance0.sub(_reserve0);
        uint amount1 = balance1.sub(_reserve1);

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        if (_totalSupply == 0) {
            address migrator = IUniswapV2Factory(factory).migrator();
            if (msg.sender == migrator) {
                liquidity = IMigrator(migrator).desiredLiquidity();
                require(liquidity > 0 && liquidity != uint256(-1), "Bad desired liquidity");
            } else {
                require(migrator == address(0), "Must not have migrator");
                liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
                _mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
            }
        } else {
            liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
        }
        require(liquidity > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED');
        _mint(to, liquidity);

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Mint(msg.sender, amount0, amount1);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function burn(address to) external lock returns (uint amount0, uint amount1) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        address _token0 = token0;                                // gas savings
        address _token1 = token1;                                // gas savings
        uint balance0 = IERC20Uniswap(_token0).balanceOf(address(this));
        uint balance1 = IERC20Uniswap(_token1).balanceOf(address(this));
        uint liquidity = balanceOf[address(this)];

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
        amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
        require(amount0 > 0 && amount1 > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_BURNED');
        _burn(address(this), liquidity);
        _safeTransfer(_token0, to, amount0);
        _safeTransfer(_token1, to, amount1);
        balance0 = IERC20Uniswap(_token0).balanceOf(address(this));
        balance1 = IERC20Uniswap(_token1).balanceOf(address(this));

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Burn(msg.sender, amount0, amount1, to);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
        require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT');
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY');

        uint balance0;
        uint balance1;
        { // scope for _token{0,1}, avoids stack too deep errors
        address _token0 = token0;
        address _token1 = token1;
        require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO');
        if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
        if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
        if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data);
        balance0 = IERC20Uniswap(_token0).balanceOf(address(this));
        balance1 = IERC20Uniswap(_token1).balanceOf(address(this));
        }
        uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
        uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
        require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT');
        { // scope for reserve{0,1}Adjusted, avoids stack too deep errors
        uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3));
        uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3));
        require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K');
        }

        _update(balance0, balance1, _reserve0, _reserve1);
        emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
    }

    // force balances to match reserves
    function skim(address to) external lock {
        address _token0 = token0; // gas savings
        address _token1 = token1; // gas savings
        _safeTransfer(_token0, to, IERC20Uniswap(_token0).balanceOf(address(this)).sub(reserve0));
        _safeTransfer(_token1, to, IERC20Uniswap(_token1).balanceOf(address(this)).sub(reserve1));
    }

    // force reserves to match balances
    function sync() external lock {
        _update(IERC20Uniswap(token0).balanceOf(address(this)), IERC20Uniswap(token1).balanceOf(address(this)), reserve0, reserve1);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
import "./ERC20.sol";
import "@openzeppelin/contracts/utils/cryptography/draft-EIP712.sol";
import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
contract OpenDAO is ERC20, EIP712 {
    uint256 public constant MAX_SUPPLY = uint248(1e14 ether);
    // for DAO.
    uint256 public constant AMOUNT_DAO = MAX_SUPPLY / 100 * 20;
    address public constant ADDR_DAO = 0x06bB1467b38d726b3eb39eB2FBAE6021feAE935F;
    // for staking
    uint256 public constant AMOUNT_STAKING = MAX_SUPPLY / 100 * 20;
    address public constant ADDR_STAKING = 0x7d28988391034A4C756f0c3E1A3E033175B04C77;
    // for liquidity providers
    uint256 public constant AMOUNT_LP = MAX_SUPPLY / 100 * 10;
    address public constant ADDR_LP = 0x709CD2aAAe592930616720115b6a3Dbdf1407664;
    // for airdrop
    uint256 public constant AMOUNT_AIREDROP = MAX_SUPPLY - (AMOUNT_DAO + AMOUNT_STAKING + AMOUNT_LP);
    constructor(string memory _name, string memory _symbol, address _signer) ERC20(_name, _symbol) EIP712("OpenDAO", "1") {
        _mint(ADDR_DAO, AMOUNT_DAO);
        _mint(ADDR_STAKING, AMOUNT_STAKING);
        _mint(ADDR_LP, AMOUNT_LP);
        _totalSupply = AMOUNT_DAO + AMOUNT_STAKING + AMOUNT_LP;
        cSigner = _signer;
    }
    bytes32 constant public MINT_CALL_HASH_TYPE = keccak256("mint(address receiver,uint256 amount)");
    address public immutable cSigner;
    function claim(uint256 amountV, bytes32 r, bytes32 s) external {
        uint256 amount = uint248(amountV);
        uint8 v = uint8(amountV >> 248);
        uint256 total = _totalSupply + amount;
        require(total <= MAX_SUPPLY, "OpenDAO: Exceed max supply");
        require(minted(msg.sender) == 0, "OpenDAO: Claimed");
        bytes32 digest = keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
32", 
            ECDSA.toTypedDataHash(_domainSeparatorV4(),
                keccak256(abi.encode(MINT_CALL_HASH_TYPE, msg.sender, amount))
        )));
        require(ecrecover(digest, v, r, s) == cSigner, "OpenDAO: Invalid signer");
        _totalSupply = total;
        _mint(msg.sender, amount);
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (token/ERC20/ERC20.sol)
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/interfaces/IERC20.sol";
import "@openzeppelin/contracts/interfaces/IERC20Metadata.sol";
import "@openzeppelin/contracts/utils/Context.sol";
/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    struct MintBalance {
        uint8 minted;
        uint248 balance;
    }
    mapping(address => MintBalance) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;
    uint256 internal _totalSupply;
    string private _name;
    string private _symbol;
    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }
    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }
    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }
    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless this function is
     * overridden;
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }
    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }
    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account].balance;
    }
    function minted(address account) public view returns (uint256) {
        return _balances[account].minted;
    }
    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }
    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }
    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }
    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        unchecked {
            _approve(sender, _msgSender(), currentAllowance - amount);
        }
        return true;
    }
    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }
    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(_msgSender(), spender, currentAllowance - subtractedValue);
        }
        return true;
    }
    /**
     * @dev Moves `amount` of tokens from `sender` to `recipient`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");
        _beforeTokenTransfer(sender, recipient, amount);
        uint256 senderBalance = _balances[sender].balance;
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[sender].balance = uint248(senderBalance - amount);
        }
        _balances[recipient].balance += uint248(amount);
        emit Transfer(sender, recipient, amount);
        _afterTokenTransfer(sender, recipient, amount);
    }
    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        // require(account != address(0), "ERC20: mint to the zero address");
        // _beforeTokenTransfer(address(0), account, amount);
        // _totalSupply += amount;
        uint256 b = _balances[account].balance + amount;
        _balances[account].balance = uint248(b);
        _balances[account].minted = 1;
        emit Transfer(address(0), account, amount);
        // _afterTokenTransfer(address(0), account, amount);
    }
    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");
        _beforeTokenTransfer(account, address(0), amount);
        uint256 accountBalance = _balances[account].balance;
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account].balance = uint248(accountBalance - amount);
        }
        _totalSupply -= amount;
        emit Transfer(account, address(0), amount);
        _afterTokenTransfer(account, address(0), amount);
    }
    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }
    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./ECDSA.sol";
/**
 * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
 *
 * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
 * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
 * they need in their contracts using a combination of `abi.encode` and `keccak256`.
 *
 * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
 * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
 * ({_hashTypedDataV4}).
 *
 * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
 * the chain id to protect against replay attacks on an eventual fork of the chain.
 *
 * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
 * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
 *
 * _Available since v3.4._
 */
abstract contract EIP712 {
    /* solhint-disable var-name-mixedcase */
    // Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
    // invalidate the cached domain separator if the chain id changes.
    bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
    uint256 private immutable _CACHED_CHAIN_ID;
    bytes32 private immutable _HASHED_NAME;
    bytes32 private immutable _HASHED_VERSION;
    bytes32 private immutable _TYPE_HASH;
    /* solhint-enable var-name-mixedcase */
    /**
     * @dev Initializes the domain separator and parameter caches.
     *
     * The meaning of `name` and `version` is specified in
     * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
     *
     * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
     * - `version`: the current major version of the signing domain.
     *
     * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
     * contract upgrade].
     */
    constructor(string memory name, string memory version) {
        bytes32 hashedName = keccak256(bytes(name));
        bytes32 hashedVersion = keccak256(bytes(version));
        bytes32 typeHash = keccak256(
            "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
        );
        _HASHED_NAME = hashedName;
        _HASHED_VERSION = hashedVersion;
        _CACHED_CHAIN_ID = block.chainid;
        _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
        _TYPE_HASH = typeHash;
    }
    /**
     * @dev Returns the domain separator for the current chain.
     */
    function _domainSeparatorV4() internal view returns (bytes32) {
        if (block.chainid == _CACHED_CHAIN_ID) {
            return _CACHED_DOMAIN_SEPARATOR;
        } else {
            return _buildDomainSeparator(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION);
        }
    }
    function _buildDomainSeparator(
        bytes32 typeHash,
        bytes32 nameHash,
        bytes32 versionHash
    ) private view returns (bytes32) {
        return keccak256(abi.encode(typeHash, nameHash, versionHash, block.chainid, address(this)));
    }
    /**
     * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
     * function returns the hash of the fully encoded EIP712 message for this domain.
     *
     * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
     *
     * ```solidity
     * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
     *     keccak256("Mail(address to,string contents)"),
     *     mailTo,
     *     keccak256(bytes(mailContents))
     * )));
     * address signer = ECDSA.recover(digest, signature);
     * ```
     */
    function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
        return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
    }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    enum RecoverError {
        NoError,
        InvalidSignature,
        InvalidSignatureLength,
        InvalidSignatureS,
        InvalidSignatureV
    }
    function _throwError(RecoverError error) private pure {
        if (error == RecoverError.NoError) {
            return; // no error: do nothing
        } else if (error == RecoverError.InvalidSignature) {
            revert("ECDSA: invalid signature");
        } else if (error == RecoverError.InvalidSignatureLength) {
            revert("ECDSA: invalid signature length");
        } else if (error == RecoverError.InvalidSignatureS) {
            revert("ECDSA: invalid signature 's' value");
        } else if (error == RecoverError.InvalidSignatureV) {
            revert("ECDSA: invalid signature 'v' value");
        }
    }
    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature` or error string. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     *
     * Documentation for signature generation:
     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
     *
     * _Available since v4.3._
     */
    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
        // Check the signature length
        // - case 65: r,s,v signature (standard)
        // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
        if (signature.length == 65) {
            bytes32 r;
            bytes32 s;
            uint8 v;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            assembly {
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
            return tryRecover(hash, v, r, s);
        } else if (signature.length == 64) {
            bytes32 r;
            bytes32 vs;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            assembly {
                r := mload(add(signature, 0x20))
                vs := mload(add(signature, 0x40))
            }
            return tryRecover(hash, r, vs);
        } else {
            return (address(0), RecoverError.InvalidSignatureLength);
        }
    }
    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, signature);
        _throwError(error);
        return recovered;
    }
    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
     *
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address, RecoverError) {
        bytes32 s;
        uint8 v;
        assembly {
            s := and(vs, 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
            v := add(shr(255, vs), 27)
        }
        return tryRecover(hash, v, r, s);
    }
    /**
     * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
     *
     * _Available since v4.2._
     */
    function recover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, r, vs);
        _throwError(error);
        return recovered;
    }
    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
     * `r` and `s` signature fields separately.
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address, RecoverError) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return (address(0), RecoverError.InvalidSignatureS);
        }
        if (v != 27 && v != 28) {
            return (address(0), RecoverError.InvalidSignatureV);
        }
        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            return (address(0), RecoverError.InvalidSignature);
        }
        return (signer, RecoverError.NoError);
    }
    /**
     * @dev Overload of {ECDSA-recover} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
        _throwError(error);
        return recovered;
    }
    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
32", hash));
    }
    /**
     * @dev Returns an Ethereum Signed Typed Data, created from a
     * `domainSeparator` and a `structHash`. This produces hash corresponding
     * to the one signed with the
     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
     * JSON-RPC method as part of EIP-712.
     *
     * See {recover}.
     */
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\\x19\\x01", domainSeparator, structHash));
    }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../token/ERC20/IERC20.sol";
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../token/ERC20/extensions/IERC20Metadata.sol";
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }
    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);
    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);
    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);
    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);
    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);
    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);
    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../IERC20.sol";
/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);
    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);
    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// Copyright (C) 2015, 2016, 2017 Dapphub

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.4.18;

contract WETH9 {
    string public name     = "Wrapped Ether";
    string public symbol   = "WETH";
    uint8  public decimals = 18;

    event  Approval(address indexed src, address indexed guy, uint wad);
    event  Transfer(address indexed src, address indexed dst, uint wad);
    event  Deposit(address indexed dst, uint wad);
    event  Withdrawal(address indexed src, uint wad);

    mapping (address => uint)                       public  balanceOf;
    mapping (address => mapping (address => uint))  public  allowance;

    function() public payable {
        deposit();
    }
    function deposit() public payable {
        balanceOf[msg.sender] += msg.value;
        Deposit(msg.sender, msg.value);
    }
    function withdraw(uint wad) public {
        require(balanceOf[msg.sender] >= wad);
        balanceOf[msg.sender] -= wad;
        msg.sender.transfer(wad);
        Withdrawal(msg.sender, wad);
    }

    function totalSupply() public view returns (uint) {
        return this.balance;
    }

    function approve(address guy, uint wad) public returns (bool) {
        allowance[msg.sender][guy] = wad;
        Approval(msg.sender, guy, wad);
        return true;
    }

    function transfer(address dst, uint wad) public returns (bool) {
        return transferFrom(msg.sender, dst, wad);
    }

    function transferFrom(address src, address dst, uint wad)
        public
        returns (bool)
    {
        require(balanceOf[src] >= wad);

        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
            require(allowance[src][msg.sender] >= wad);
            allowance[src][msg.sender] -= wad;
        }

        balanceOf[src] -= wad;
        balanceOf[dst] += wad;

        Transfer(src, dst, wad);

        return true;
    }
}


/*
                    GNU GENERAL PUBLIC LICENSE
                       Version 3, 29 June 2007

 Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

                            Preamble

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  The licenses for most software and other practical works are designed
to take away your freedom to share and change the works.  By contrast,
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share and change all versions of a program--to make sure it remains free
software for all its users.  We, the Free Software Foundation, use the
GNU General Public License for most of our software; it applies also to
any other work released this way by its authors.  You can apply it to
your programs, too.

  When we speak of free software, we are referring to freedom, not
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product received by a particular user, "normally used" refers to a
typical or common use of that class of product, regardless of the status
of the particular user or of the way in which the particular user
actually uses, or expects or is expected to use, the product.  A product
is a consumer product regardless of whether the product has substantial
commercial, industrial or non-consumer uses, unless such uses represent
the only significant mode of use of the product.

  "Installation Information" for a User Product means any methods,
procedures, authorization keys, or other information required to install
and execute modified versions of a covered work in that User Product from
a modified version of its Corresponding Source.  The information must
suffice to ensure that the continued functioning of the modified object
code is in no case prevented or interfered with solely because
modification has been made.

  If you convey an object code work under this section in, or with, or
specifically for use in, a User Product, and the conveying occurs as
part of a transaction in which the right of possession and use of the
User Product is transferred to the recipient in perpetuity or for a
fixed term (regardless of how the transaction is characterized), the
Corresponding Source conveyed under this section must be accompanied
by the Installation Information.  But this requirement does not apply
if neither you nor any third party retains the ability to install
modified object code on the User Product (for example, the work has
been installed in ROM).

  The requirement to provide Installation Information does not include a
requirement to continue to provide support service, warranty, or updates
for a work that has been modified or installed by the recipient, or for
the User Product in which it has been modified or installed.  Access to a
network may be denied when the modification itself materially and
adversely affects the operation of the network or violates the rules and
protocols for communication across the network.

  Corresponding Source conveyed, and Installation Information provided,
in accord with this section must be in a format that is publicly
documented (and with an implementation available to the public in
source code form), and must require no special password or key for
unpacking, reading or copying.

  7. Additional Terms.

  "Additional permissions" are terms that supplement the terms of this
License by making exceptions from one or more of its conditions.
Additional permissions that are applicable to the entire Program shall
be treated as though they were included in this License, to the extent
that they are valid under applicable law.  If additional permissions
apply only to part of the Program, that part may be used separately
under those permissions, but the entire Program remains governed by
this License without regard to the additional permissions.

  When you convey a copy of a covered work, you may at your option
remove any additional permissions from that copy, or from any part of
it.  (Additional permissions may be written to require their own
removal in certain cases when you modify the work.)  You may place
additional permissions on material, added by you to a covered work,
for which you have or can give appropriate copyright permission.

  Notwithstanding any other provision of this License, for material you
add to a covered work, you may (if authorized by the copyright holders of
that material) supplement the terms of this License with terms:

    a) Disclaiming warranty or limiting liability differently from the
    terms of sections 15 and 16 of this License; or

    b) Requiring preservation of specified reasonable legal notices or
    author attributions in that material or in the Appropriate Legal
    Notices displayed by works containing it; or

    c) Prohibiting misrepresentation of the origin of that material, or
    requiring that modified versions of such material be marked in
    reasonable ways as different from the original version; or

    d) Limiting the use for publicity purposes of names of licensors or
    authors of the material; or

    e) Declining to grant rights under trademark law for use of some
    trade names, trademarks, or service marks; or

    f) Requiring indemnification of licensors and authors of that
    material by anyone who conveys the material (or modified versions of
    it) with contractual assumptions of liability to the recipient, for
    any liability that these contractual assumptions directly impose on
    those licensors and authors.

  All other non-permissive additional terms are considered "further
restrictions" within the meaning of section 10.  If the Program as you
received it, or any part of it, contains a notice stating that it is
governed by this License along with a term that is a further
restriction, you may remove that term.  If a license document contains
a further restriction but permits relicensing or conveying under this
License, you may add to a covered work material governed by the terms
of that license document, provided that the further restriction does
not survive such relicensing or conveying.

  If you add terms to a covered work in accord with this section, you
must place, in the relevant source files, a statement of the
additional terms that apply to those files, or a notice indicating
where to find the applicable terms.

  Additional terms, permissive or non-permissive, may be stated in the
form of a separately written license, or stated as exceptions;
the above requirements apply either way.

  8. Termination.

  You may not propagate or modify a covered work except as expressly
provided under this License.  Any attempt otherwise to propagate or
modify it is void, and will automatically terminate your rights under
this License (including any patent licenses granted under the third
paragraph of section 11).

  However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly and
finally terminates your license, and (b) permanently, if the copyright
holder fails to notify you of the violation by some reasonable means
prior to 60 days after the cessation.

  Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.

  Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License.  If your rights have been terminated and not permanently
reinstated, you do not qualify to receive new licenses for the same
material under section 10.

  9. Acceptance Not Required for Having Copies.

  You are not required to accept this License in order to receive or
run a copy of the Program.  Ancillary propagation of a covered work
occurring solely as a consequence of using peer-to-peer transmission
to receive a copy likewise does not require acceptance.  However,
nothing other than this License grants you permission to propagate or
modify any covered work.  These actions infringe copyright if you do
not accept this License.  Therefore, by modifying or propagating a
covered work, you indicate your acceptance of this License to do so.

  10. Automatic Licensing of Downstream Recipients.

  Each time you convey a covered work, the recipient automatically
receives a license from the original licensors, to run, modify and
propagate that work, subject to this License.  You are not responsible
for enforcing compliance by third parties with this License.

  An "entity transaction" is a transaction transferring control of an
organization, or substantially all assets of one, or subdividing an
organization, or merging organizations.  If propagation of a covered
work results from an entity transaction, each party to that
transaction who receives a copy of the work also receives whatever
licenses to the work the party's predecessor in interest had or could
give under the previous paragraph, plus a right to possession of the
Corresponding Source of the work from the predecessor in interest, if
the predecessor has it or can get it with reasonable efforts.

  You may not impose any further restrictions on the exercise of the
rights granted or affirmed under this License.  For example, you may
not impose a license fee, royalty, or other charge for exercise of
rights granted under this License, and you may not initiate litigation
(including a cross-claim or counterclaim in a lawsuit) alleging that
any patent claim is infringed by making, using, selling, offering for
sale, or importing the Program or any portion of it.

  11. Patents.

  A "contributor" is a copyright holder who authorizes use under this
License of the Program or a work on which the Program is based.  The
work thus licensed is called the contributor's "contributor version".

  A contributor's "essential patent claims" are all patent claims
owned or controlled by the contributor, whether already acquired or
hereafter acquired, that would be infringed by some manner, permitted
by this License, of making, using, or selling its contributor version,
but do not include claims that would be infringed only as a
consequence of further modification of the contributor version.  For
purposes of this definition, "control" includes the right to grant
patent sublicenses in a manner consistent with the requirements of
this License.

  Each contributor grants you a non-exclusive, worldwide, royalty-free
patent license under the contributor's essential patent claims, to
make, use, sell, offer for sale, import and otherwise run, modify and
propagate the contents of its contributor version.

  In the following three paragraphs, a "patent license" is any express
agreement or commitment, however denominated, not to enforce a patent
(such as an express permission to practice a patent or covenant not to
sue for patent infringement).  To "grant" such a patent license to a
party means to make such an agreement or commitment not to enforce a
patent against the party.

  If you convey a covered work, knowingly relying on a patent license,
and the Corresponding Source of the work is not available for anyone
to copy, free of charge and under the terms of this License, through a
publicly available network server or other readily accessible means,
then you must either (1) cause the Corresponding Source to be so
available, or (2) arrange to deprive yourself of the benefit of the
patent license for this particular work, or (3) arrange, in a manner
consistent with the requirements of this License, to extend the patent
license to downstream recipients.  "Knowingly relying" means you have
actual knowledge that, but for the patent license, your conveying the
covered work in a country, or your recipient's use of the covered work
in a country, would infringe one or more identifiable patents in that
country that you have reason to believe are valid.

  If, pursuant to or in connection with a single transaction or
arrangement, you convey, or propagate by procuring conveyance of, a
covered work, and grant a patent license to some of the parties
receiving the covered work authorizing them to use, propagate, modify
or convey a specific copy of the covered work, then the patent license
you grant is automatically extended to all recipients of the covered
work and works based on it.

  A patent license is "discriminatory" if it does not include within
the scope of its coverage, prohibits the exercise of, or is
conditioned on the non-exercise of one or more of the rights that are
specifically granted under this License.  You may not convey a covered
work if you are a party to an arrangement with a third party that is
in the business of distributing software, under which you make payment
to the third party based on the extent of your activity of conveying
the work, and under which the third party grants, to any of the
parties who would receive the covered work from you, a discriminatory
patent license (a) in connection with copies of the covered work
conveyed by you (or copies made from those copies), or (b) primarily
for and in connection with specific products or compilations that
contain the covered work, unless you entered into that arrangement,
or that patent license was granted, prior to 28 March 2007.

  Nothing in this License shall be construed as excluding or limiting
any implied license or other defenses to infringement that may
otherwise be available to you under applicable patent law.

  12. No Surrender of Others' Freedom.

  If conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License.  If you cannot convey a
covered work so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you may
not convey it at all.  For example, if you agree to terms that obligate you
to collect a royalty for further conveying from those to whom you convey
the Program, the only way you could satisfy both those terms and this
License would be to refrain entirely from conveying the Program.

  13. Use with the GNU Affero General Public License.

  Notwithstanding any other provision of this License, you have
permission to link or combine any covered work with a work licensed
under version 3 of the GNU Affero General Public License into a single
combined work, and to convey the resulting work.  The terms of this
License will continue to apply to the part which is the covered work,
but the special requirements of the GNU Affero General Public License,
section 13, concerning interaction through a network will apply to the
combination as such.

  14. Revised Versions of this License.

  The Free Software Foundation may publish revised and/or new versions of
the GNU General Public License from time to time.  Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.

  Each version is given a distinguishing version number.  If the
Program specifies that a certain numbered version of the GNU General
Public License "or any later version" applies to it, you have the
option of following the terms and conditions either of that numbered
version or of any later version published by the Free Software
Foundation.  If the Program does not specify a version number of the
GNU General Public License, you may choose any version ever published
by the Free Software Foundation.

  If the Program specifies that a proxy can decide which future
versions of the GNU General Public License can be used, that proxy's
public statement of acceptance of a version permanently authorizes you
to choose that version for the Program.

  Later license versions may give you additional or different
permissions.  However, no additional obligations are imposed on any
author or copyright holder as a result of your choosing to follow a
later version.

  15. Disclaimer of Warranty.

  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

  16. Limitation of Liability.

  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES.

  17. Interpretation of Sections 15 and 16.

  If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely approximates
an absolute waiver of all civil liability in connection with the
Program, unless a warranty or assumption of liability accompanies a
copy of the Program in return for a fee.

                     END OF TERMS AND CONDITIONS

            How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

Also add information on how to contact you by electronic and paper mail.

  If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:

    <program>  Copyright (C) <year>  <name of author>
    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, your program's commands
might be different; for a GUI interface, you would use an "about box".

  You should also get your employer (if you work as a programmer) or school,
if any, to sign a "copyright disclaimer" for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<http://www.gnu.org/licenses/>.

  The GNU General Public License does not permit incorporating your program
into proprietary programs.  If your program is a subroutine library, you
may consider it more useful to permit linking proprietary applications with
the library.  If this is what you want to do, use the GNU Lesser General
Public License instead of this License.  But first, please read
<http://www.gnu.org/philosophy/why-not-lgpl.html>.

*/