#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
string s;
string numbers = "0123456789";
string lower_case = "abcdefghijklmnopqrstuvwxyz";
string upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
string special_characters = "!@#$%^&*()-+";
bool hasn = false;
bool hasl = false;
bool hasu = false;
bool hass = false;
    
int n;
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    cin>> n;
    cin >> s;
    int count = 0;
    for (int i =0; i <n; i++) {
        if ( numbers.find (s.at(i)) != string::npos){
            hasn = true;
        }
        if (lower_case.find (s.at(i)) != string::npos){
            hasl = true;
        }
        if ( upper_case.find (s.at(i)) != string::npos){
            hasu = true;
        }
        if (special_characters.find (s.at(i)) != string::npos){
            hass = true;
        }
        if (hasn && hasl && hasu && hass){
            break;
        }
      }
    
    if (hasn){
        count ++;
    } 
    if ( hasl){
        count ++;
    }
    if (hasu){
        count ++;
    }
    if (hass){
        count ++;
    }
    if (n + (4 -count) < 6){
           cout << 6 - n;
       }     
    else{ 

         cout << 4-count;
    }
    
          
    
    
    return 0;
}