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 charsToAdd = 0;
        if(n < 6) charsToAdd = 6 - n;
        int corrections = 0;
        boolean digit = false;
        boolean lower = false;
        boolean upper = false;
        boolean special = false;
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
        for(int i = 0; i < password.length(); i++){
            if (numbers.indexOf(password.charAt(i)) != -1){
                digit = true;
                continue;
            }
            if (lower_case.indexOf(password.charAt(i)) != -1){
                lower = true;
                continue;
            }
            if (upper_case.indexOf(password.charAt(i)) != -1){
                upper = true;
                continue;
            }
            if (special_characters.indexOf(password.charAt(i)) != -1){
                special = true;
                continue;
            }
            if(digit && upper && lower && special){
                break;
            }
        }
        if(!digit) corrections++;
        if(!lower) corrections++;
        if(!upper) corrections++;
        if(!special) corrections++;
        if(charsToAdd < corrections) charsToAdd = corrections;
        return charsToAdd;
    }

    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();
    }
}