func_code_string: #include <bits/stdc++.h>   int main() {     uint64_t a, b, x;     std::cin >> a >> b;     a < b | a - b & 1         ? std::cout << -1         : (x = a - b >> 1,            x ^ a - x ^ b ? std::cout << -1 : std::cout << x <<     << a - x);   }   