func_code_string: #include <bits/stdc++.h>   using namespace std;   int s[50];   char a[55][55];   int main() {     int n, i, j, c = 1, k, found;     scanf( %d , &n);     for (i = 0; i < n; i++) {       scanf( %s , a[i]);       int l = strlen(a[i]);       for (j = 0; j < l; j++) {         s[a[i][j] -  a ]++;       }     }     for (i = 0; i < 26; i++) {       if (s[i] == 0) {         printf( %c , (char)(i +  a ));         c = 1;         break;       } else         c = 2;     }     if (c == 2) {       for (i = 0; i < 26; i++) {         for (j = 0; j < 26; j++) {           char str[4];           found = 0;           str[0] = (char)(i +  a );           str[1] = (char)(j +  a );           for (k = 0; k < n; k++) {             int l = strlen(a[k]), x = 0;             while (x < (l - 1)) {               if (a[k][x] == str[0] && a[k][x + 1] == str[1]) {                 found = 1;                 break;               } else                 x++;             }             if (found == 1) break;           }           if (found == 0) {             printf( %c%c n , str[0], str[1]);             c = 3;             break;           }         }         if (c == 3) break;       }     }     return 0;   }   