func_code_string: #include <bits/stdc++.h>   using namespace std;   unsigned long long a, b;   int main() {     cin >> a >> b;     if ((a + b) % 2 == 0)       cout << (a - b) / 2 <<     << (a + b) / 2 << endl;     else       cout << -1 << endl;     return 0;   }   