func_code_string: #include <bits/stdc++.h>   using namespace std;   int N, M;   int main() {     cin >> M >> N;     if (M == N) {       cout << N <<  1  <<     << N <<  2 ;       return 0;     }     if (N - M == 1) {       cout << M <<  9  <<     << N <<  0 ;       return 0;     }     if (M == 9 && N == 1) {       cout <<  9 10 ;       return 0;     }     cout << -1;   }   