// SPDX-License-Identifier: MIT


// ------------------------------------------------------------------------
// MIT License
// Copyright (c) 2020 Yearn Finance Passive Income
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
// ------------------------------------------------------------------------    

    pragma solidity ^0.5.16;

    interface IERC20 {
        function totalSupply() external view returns (uint);
        function balanceOf(address account) external view returns (uint);
        function transfer(address recipient, uint amount) external returns (bool);
        function allowance(address owner, address spender) external view returns (uint);
        function approve(address spender, uint amount) external returns (bool);
        function transferFrom(address sender, address recipient, uint amount) external returns (bool);
        event Transfer(address indexed from, address indexed to, uint value);
        event Approval(address indexed owner, address indexed spender, uint value);
    }

    contract Context {
        constructor () internal { }
        // solhint-disable-previous-line no-empty-blocks

        function _msgSender() internal view returns (address payable) {
            return msg.sender;
        }
    }

    contract ERC20 is Context, IERC20 {
        using SafeMath for uint;

        mapping (address => uint) private _balances;

        mapping (address => mapping (address => uint)) private _allowances;

        uint private _totalSupply;
        function totalSupply() public view returns (uint) {
            return _totalSupply;
        }
        function balanceOf(address account) public view returns (uint) {
            return _balances[account];
        }
        function transfer(address recipient, uint amount) public returns (bool) {
            _transfer(_msgSender(), recipient, amount);
            return true;
        }
        function allowance(address owner, address spender) public view returns (uint) {
            return _allowances[owner][spender];
        }
        function approve(address spender, uint amount) public returns (bool) {
            _approve(_msgSender(), spender, amount);
            return true;
        }
        function transferFrom(address sender, address recipient, uint amount) public returns (bool) {
            _transfer(sender, recipient, amount);
            _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
            return true;
        }
        function increaseAllowance(address spender, uint addedValue) public returns (bool) {
            _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
            return true;
        }
        function decreaseAllowance(address spender, uint subtractedValue) public returns (bool) {
            _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
            return true;
        }
        function _transfer(address sender, address recipient, uint amount) internal {
            require(sender != address(0), "ERC20: transfer from the zero address");
            require(recipient != address(0), "ERC20: transfer to the zero address");

            _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
            _balances[recipient] = _balances[recipient].add(amount);
            emit Transfer(sender, recipient, amount);
        }
        function _mint(address account, uint amount) internal {
            require(account != address(0), "ERC20: mint to the zero address");

            _totalSupply = _totalSupply.add(amount);
            _balances[account] = _balances[account].add(amount);
            emit Transfer(address(0), account, amount);
        }
        function _burn(address account, uint amount) internal {
            require(account != address(0), "ERC20: burn from the zero address");
            require(_balances[account] >= amount);
            _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
            _totalSupply = _totalSupply.sub(amount);
            emit Transfer(account, address(0), amount);
        }
        function _approve(address owner, address spender, uint amount) internal {
            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);
        }
    }

    contract ERC20Detailed is IERC20 {
        string private _name;
        string private _symbol;
        uint8 private _decimals;

        constructor (string memory name, string memory symbol, uint8 decimals) public {
            _name = name;
            _symbol = symbol;
            _decimals = decimals;
        }
        function name() public view returns (string memory) {
            return _name;
        }
        function symbol() public view returns (string memory) {
            return _symbol;
        }
        function decimals() public view returns (uint8) {
            return _decimals;
        }
    }

    library SafeMath {
        function add(uint a, uint b) internal pure returns (uint) {
            uint c = a + b;
            require(c >= a, "SafeMath: addition overflow");

            return c;
        }
        function sub(uint a, uint b) internal pure returns (uint) {
            return sub(a, b, "SafeMath: subtraction overflow");
        }
        function sub(uint a, uint b, string memory errorMessage) internal pure returns (uint) {
            require(b <= a, errorMessage);
            uint c = a - b;

            return c;
        }
        function mul(uint a, uint b) internal pure returns (uint) {
            if (a == 0) {
                return 0;
            }

            uint c = a * b;
            require(c / a == b, "SafeMath: multiplication overflow");

            return c;
        }
        function div(uint a, uint b) internal pure returns (uint) {
            return div(a, b, "SafeMath: division by zero");
        }
        function div(uint a, uint b, string memory errorMessage) internal pure returns (uint) {
            // Solidity only automatically asserts when dividing by 0
            require(b > 0, errorMessage);
            uint c = a / b;

            return c;
        }
    }

    library Address {
        function isContract(address account) internal view returns (bool) {
            bytes32 codehash;
            bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
            // solhint-disable-next-line no-inline-assembly
            assembly { codehash := extcodehash(account) }
            return (codehash != 0x0 && codehash != accountHash);
        }
    }

    library SafeERC20 {
        using SafeMath for uint;
        using Address for address;

        function safeTransfer(IERC20 token, address to, uint value) internal {
            callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
        }

        function safeTransferFrom(IERC20 token, address from, address to, uint value) internal {
            callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
        }

        function safeApprove(IERC20 token, address spender, uint value) internal {
            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 callOptionalReturn(IERC20 token, bytes memory data) private {
            require(address(token).isContract(), "SafeERC20: call to non-contract");

            // solhint-disable-next-line avoid-low-level-calls
            (bool success, bytes memory returndata) = address(token).call(data);
            require(success, "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");
            }
        }
    }

    contract YFPI is ERC20, ERC20Detailed {
    using SafeERC20 for IERC20;
    using Address for address;
    using SafeMath for uint;
       
    address public owner;

    constructor () public ERC20Detailed("Yearn Finance Passive Income", "YFPI", 18) {
        owner = msg.sender;
        _mint(_msgSender(), 30000 * (10 ** uint256(decimals())));
    }

    function burn(uint amount) public {
         _burn(msg.sender, amount);
    }
    

    }