func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string str1, str2;     cin >> str1 >> str2;     int siz = str1.size();     siz--;     while (siz > -1) {       if (str1[siz] ==  z ) {         str1[siz] =  a ;         siz--;       } else {         str1[siz]++;         break;       }     }     if (siz == -1 || str1 == str2)       cout <<  No such string  << endl;     else       cout << str1 << endl;     return 0;   }   