1914A - Problemsolving Log - CodeForces Solution

/*
   author : phukao
*/
#include <bits/stdc++.h>
using namespace std;

#ifdef LOCAL
   #include "debug.h"
#else
   #define dbg(x)
#endif

int main(){
   ios::sync_with_stdio(false);
   cin.tie(0);
   int tc;
   cin >> tc;
   while(tc--){
      int n;
      cin >> n;
      string s;
      cin >> s;
      vector<int> v(26,0);
      for(auto c : s){
         v[c-'A']++;
      }
      int num=0;
      for(int i=0;i<26;i++){
         if(v[i] >= i+1){
            num++;
         }
      }
      cout << num << '\n';
   }
}