func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int i, j, k, l, m, n, ok = 0;     char s1[110], s2[110], ans[110];     scanf( %s , s1);     scanf( %s , s2);     l = strlen(s1);     for (i = 0; i < l; i++) {       if (s1[i] > s2[i]) {         ans[i] = s2[i];       } else if (s1[i] < s2[i]) {         ok = 1;         break;       } else         ans[i] = s1[i];     }     ans[l] =   0 ;     if (ok)       printf( -1 n );     else       puts(ans);     return 0;   }   