// Vulnerability label: overflow
pragma solidity ^0.4.25;

contract tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; }

contract BlockEstateToken {
    string public version = '0.1';
    string public name;
    string public symbol;
    uint8 public decimals;
    address public owner;
    uint256 public _totalSupply;

    mapping (address => uint256) public balances;
    mapping (address => mapping (address => uint256)) public allowances;

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Burn(address indexed from, uint256 value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);

    function BlockEstateToken() public {
        balances[msg.sender] = 10000000000000000;
        _totalSupply = 10000000000000000;
        name = 'BlockEstate';
        symbol = 'BIT';
        decimals = 8;
        owner = msg.sender;
    }

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

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

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

    function transfer(address _to, uint256 _value) public returns (bool success) {
        if (_to == 0x0) return false;
        if (balances[msg.sender] < _value) return false;
        if (balances[_to] + _value < balances[_to]) return false;
        balances[msg.sender] -= _value;
        balances[_to] += _value;
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

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

    function approveAndCall(address _spender, uint256 _value, bytes _extraData) public returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
    }        

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        if (_to == 0x0) return false;
        if (balances[_from] < _value) return false;
        if (balances[_to] + _value < balances[_to]) return false;
        if (_value > allowances[_from][msg.sender]) return false;
        balances[_from] -= _value;
        balances[_to] += _value;
        allowances[_from][msg.sender] -= _value;
        emit Transfer(_from, _to, _value);
        return true;
    }

    function burn(uint256 _value) public returns (bool success) {
        if (balances[msg.sender] < _value) return false;
        balances[msg.sender] -= _value;
        _totalSupply -= _value;
        emit Burn(msg.sender, _value);
        return true;
    }

    function burnFrom(address _from, uint256 _value) public returns (bool success) {
        if (balances[_from] < _value) return false;
        if (_value > allowances[_from][msg.sender]) return false;
        balances[_from] -= _value;
        _totalSupply -= _value;
        emit Burn(_from, _value);
        return true;
    }
}