#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    // Return the minimum number of characters to make the password strong
        string numbers = "0123456789";
    string lower_case = "abcdefghijklmnopqrstuvwxyz";
    string upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    string special_characters = "!@#$%^&*()-+";
    int i,count=0;
    int flagl,flagu,flagn,flags;
    flagl=flagu=flagn=flags=1;
    
    for(i=0;i<n;i++)
    {
      if(lower_case.find(password[i])<26 && flagl==1)
        {
          count++;
          flagl=0;
        }
      else if(upper_case.find(password[i])<26 && flagu==1)
        {
          count++;
          flagu=0;
        }
      else if(numbers.find(password[i])<11 && flagn==1)
        {
          count++;
          flagn=0;
        }
      else if(special_characters.find(password[i])<15 && flags==1)
        { 
          count++;
          flags=0;
        }
      //cout<<"\ncurrent"<<count;
    }
    if(n>=6 && count==4)
      return 0;
    else if(count<4 && n>=6)
      return (4-count);
    else if(n<6)
      {
        if(n+4-count>=6)
          return 4-count;
        else
          return 6-n;
      }
    return 0;
}

int main() {
    int n;
    cin >> n;
    string password;
    cin >> password;
    int answer = minimumNumber(n, password);
    cout << answer << endl;
    return 0;
}