// File: ERC20Standard.sol



pragma solidity ^0.5.7;

library SafeMath {

    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0);
        uint256 c = a / b;

    return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}

contract ERC20Standard {
    using SafeMath for uint256;
    uint public totalSupply;

    string public name;
    uint8 public decimals;
    string public symbol;
    string public version;

    mapping (address => uint256) balances;
    mapping (address => mapping (address => uint)) allowed;

    //Fix for short address attack against ERC20
    modifier onlyPayloadSize(uint size) {
        assert(msg.data.length == size + 4);
        _;
    }

    function balanceOf(address _owner) public view returns (uint balance) {
        return balances[_owner];
    }

    function transfer(address _recipient, uint _value) public onlyPayloadSize(2*32) {
        require(balances[msg.sender] >= _value && _value > 0);
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_recipient] = balances[_recipient].add(_value);
        emit Transfer(msg.sender, _recipient, _value);
        }

    function transferFrom(address _from, address _to, uint _value) public {
        require(balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0);
            balances[_to] = balances[_to].add(_value);
            balances[_from] = balances[_from].sub(_value);
            allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
            emit Transfer(_from, _to, _value);
        }

    function  approve(address _spender, uint _value) public {
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
    }

    function allowance(address _spender, address _owner) public view returns (uint balance) {
        return allowed[_owner][_spender];
    }

    //Event which is triggered to log all transfers to this contract's event log
    event Transfer(
        address indexed _from,
        address indexed _to,
        uint _value
        );

    //Event which is triggered whenever an owner approves a new allowance for a spender.
    event Approval(
        address indexed _owner,
        address indexed _spender,
        uint _value
        );
}

// File: XTToken.sol



pragma solidity ^0.5.7;

import "./ERC20Standard.sol";

contract XTToken is ERC20Standard {
    constructor() public {
        totalSupply = 1000000000000000000000000000;
        name = "ExtStock Token";
        decimals = 18;
        symbol = "XT";
        version = "1.0";
        balances[msg.sender] = totalSupply;
    }
}