interface IERC20 {
    //function transfer(address to, uint256 value) external returns (bool);

    //function approve(address spender, uint256 value) external returns (bool);

    //function transferFrom(address from, address to, uint256 value) external returns (bool);

    function totalSupply() external view returns (uint256);

    function balanceOf(address who) external view returns (uint256);

    //function allowance(address owner, address spender) external view returns (uint256);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(address indexed owner, address indexed spender, uint256 value);
}
function totalSupply() external view returns (uint256);

//function transfer(address to, uint256 value) external returns (bool);
//function approve(address spender, uint256 value) external returns (bool);
//function transferFrom(address from, address to, uint256 value) external returns (bool);