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

public class Solution {

    static String numbers = "0123456789";
    static String lower_case = "abcdefghijklmnopqrstuvwxyz";
    static String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    static String special_characters = "!@#$%^&*()-+";

    static int minimumNumber(int n, String password) {

        int length = 6 - password.length();
        boolean digit = false;
        boolean lower = false;
        boolean upper = false;
        boolean special = false;
        for (int i = 0; i < password.length(); i++) {
            String c = String.valueOf(password.charAt(i));
            if (numbers.contains(c)) {
                digit = true;
            }
            if (lower_case.contains(c)) {
                lower = true;
            }
            if (upper_case.contains(c)) {
                upper = true;
            }
            if (special_characters.contains(c)) {
                special = true;
            }


        }
        int result = 0;
        if (!digit) result++;
        if (!lower) result++;
        if (!upper) result++;
        if (!special) result++;

        if(length <= 0) return result;
        else return Math.max(length,result);
    }

    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();
    }
}