SVATT2017

"pragma solidity ^0.4.18;

contract ctf {
address public owner;
// uint public secret;
uint private flag; //no public, it's a secret;

/* CONSTRUCTOR */
function ctf(uint _flag) public {
owner = msg.sender;
flag = _flag;
}

/* let me change the secret just in case I want to */
// deployed at https://etherscan.io/address/0xeec8a45a3406c8cf1de7ba0083b1c8dd2e31a27f
function change_flag(uint newflag, uint key) public {
require(msg.sender == owner); //make sure it's me
flag = newflag^key;
}

function() payable public {
return;
}
// don't need it anymore
function kill(address _to) public {
require(msg.sender == owner);
selfdestruct(_to);
}
}"