import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    static int minimumNumber(int n, String password) {
         String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+" ;
        
        int extra = 4;
        boolean num = false, upper = false, lower = false, spec = false;
        for(int i = 0; i < n; i++){
            boolean flag = true;
            if(!num){
                if(numbers.contains(password.charAt(i) + "")){
                    extra--;
                    num = true;
                    flag = false;
                }
            }
            if(!lower){
                if(lower_case.contains(password.charAt(i) + "")){
                    extra--;
                    lower = true;
                    flag = false;
                 }
            }
            if(!upper){
                if(upper_case.contains(password.charAt(i) + "")){
                     upper = true;
                    extra--;
                    flag = false;
                }
                
            }
            if(!spec){
                if(special_characters.contains(password.charAt(i) + "")){
                     spec = true;
                    extra--;
                    flag = false;
                }
                   
            }
            
            
        }
        
      
        
         if(n >= 6)
           return extra;
        if(n < 6){
            if((6-n) >= extra)
                return (6-n);
            else{
                return (extra);
            }
        }
        
        return 0;
        
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String password = in.next();
        int answer = minimumNumber(n, password);
        System.out.println(answer);
        in.close();
    }
}