func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 100005;   string str[N];   int main() {     int n;     cin >> n;     for (int i = 0; i < n; i++) {       cin >> str[i];     }     for (int i = 0; i < ((int)(str[0]).size()); i++) {       bool all = true;       char only = 0;       for (int j = 0; j < n; j++) {         if (str[j][i] ==  ? ) continue;         all = false;         if (only == 0)           only = str[j][i];         else if (only != 0 && str[j][i] != only)           only = -1;       }       if (all) {         printf( a );       } else if (only != -1) {         printf( %c , only);       } else {         printf( ? );       }     }     puts(  );     return 0;   }   