func_code_string: #include <bits/stdc++.h>   using namespace std;   char st[100005];   int vis[100005];   int main() {     long l, cnt = 0;     scanf( %ld , &l);     scanf( %s , st);     if (l > 26) {       cout << -1;       return 0;     }     for (long i = 0; i < l + 10; i++) vis[i] = 0;     for (long i = 0; i < l; i++) {       if (vis[i] == 0) {         vis[i] = 1;         for (long j = i + 1; j < l; j++) {           if (st[i] == st[j] && vis[j] == 0) {             cnt++;             vis[j] = 1;           }         }       }     }     cout << cnt;     return 0;   }   