func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int a, b;     cin >> a >> b;     if (a == b)       cout << a << 0 <<     << b << 1 << endl;     else if (a + 1 == b) {       cout << a << 9 <<     << b << 0 << endl;     } else if (a == 9 && b == 1) {       cout <<  9 10  << endl;     } else {       cout << -1;     }     return 0;   }   