#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <string>
#include <cstring>
#define pb push_back
#define mp make_pair
using namespace std;
const int N=1e2+5;

int n;
string s;

int digit,capital,lower,special;

string sp="!@#$%^&*()-+";
bool is_special(char ch)
{
    for(int i=0;i<sp.size();i++)
    {
        if(ch == sp[i])
        {
            return true;
        }
    }

    return false;
}


int main()
{
  int i;

  cin>>n;
  cin>>s;

  for(i=0;i<n;i++)
  {
      if(s[i] >= '0' && s[i] <= '9')
        digit=1;

      if(s[i] >= 'A' && s[i] <= 'Z')
        capital=1;

      if(s[i] >= 'a' && s[i] <= 'z')
        lower=1;

      if(is_special(s[i]))
        special=1;
  }

  int need=4 - (digit+capital+lower+special);



  cout<<max(6 - n,need)<<endl;


  return 0;
}