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