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) {
        // Return the minimum number of characters to make the password strong
        int length = n;
        boolean specialFlag = false;
        boolean numberFlag = false;
        boolean upperCaseFalg = false;
        boolean lowerCaseFalg = false;
        int toAdd = 0;
        
        Pattern p = Pattern.compile("[^a-z0-9 ]", Pattern.CASE_INSENSITIVE);
        Matcher m = p.matcher(password);
        boolean b = m.find();

        if (b) specialFlag = true;
        
        if(password.matches(".*\\d+.*")) numberFlag = true;
        
        
        char ch;
            for(int i=0;i < password.length();i++) {
        ch = password.charAt(i);
                
        
         if (Character.isUpperCase(ch)) {
            upperCaseFalg = true;
        } else if (Character.isLowerCase(ch)) {
            lowerCaseFalg = true;
        }
       
        }
           
        
        if(specialFlag == false) toAdd++;
        if(numberFlag == false) toAdd++;
        if(upperCaseFalg == false) toAdd++;
        if(lowerCaseFalg == false) toAdd++;
        int temp = toAdd;
        if(n+toAdd < 6) {return 6-n;}
        
           
        return toAdd;
        
    }

    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();
    }
}