// Vulnerability label: clean
pragma solidity ^ 0.4.19;

interface IERC20 {
    function totalSupply() constant returns(uint256 totalSupply);
    function balanceOf(address _owner) constant returns(uint256 balance);
    function transfer(address _to, uint256 _value) returns(bool success);
    function transferFrom(address _from, address _to, uint256 _value) returns(bool success);
    function approve(address _spender, uint256 _value) returns(bool success);
    function allowance(address _owner, address _spender) constant returns(uint256 remaining);
    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns(uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        assert(c / a == b);
        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns(uint256) {
        uint256 c = a / b;
        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns(uint256) {
        assert(b <= a);
        return a - b;
    }

    function add(uint256 a, uint256 b) internal pure returns(uint256) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
    }
}

contract KeenFutureToken is IERC20 {

    using SafeMath
    for uint256;

    uint public constant _totalSupply = 10500000;

    string public constant symbol = "KFT";
    string public constant name = "Keen Future Token";
    uint8 public constant decimals = 0;

    mapping(address => uint256) balances;
    mapping(address => mapping(address => uint256)) allowed;

    function KeenFutureToken() {
        balances[msg.sender] = _totalSupply;
    }

    function totalSupply() constant returns(uint256 totalSupply) {
        return _totalSupply;
    }

    function balanceOf(address _owner) constant returns(uint256 balance) {
        return balances[_owner];
    }

    function transfer(address _to, uint256 _value) returns(bool success) {
        require(
            balances[msg.sender] >= _value &&
            _value > 0
        );
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        Transfer(msg.sender, _to, _value);
        return true;

    }

    function transferFrom(address _from, address _to, uint256 _value) returns(bool success) {
        require(
            allowed[_from][msg.sender] >= _value &&
            balances[_from] >= _value &&
            _value > 0
        );
        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        Transfer(_from, _to, _value);
        return true;
    }

    function approve(address _spender, uint256 _value) returns(bool success) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) constant returns(uint256 remaining) {
        return allowed[_owner][_spender];
    }

}