func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string x, y;     cin >> x >> y;     const auto n = int(x.size());     auto ok = true;     for (auto i = 0; i < n; i++) ok &= y[i] <= x[i];     if (ok)       cout << y << endl;     else       cout << -1 << endl;   }   