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

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

    private static int minimumNumber(int n, String password) {
        boolean hasNumbers = false, hasLower = false, hasUpper = false, hasSpecial = false;
        for (int i = 0; i < password.length(); i++) {
            final String s = String.valueOf(password.charAt(i));
            if (numbers.contains(s)) {
                hasNumbers = true;
            } else if (lower_case.contains(s)) {
                hasLower = true;
            } else if (upper_case.contains(s)) {
                hasUpper = true;
            } else if (special_characters.contains(s)) {
                hasSpecial = true;
            }
        }

        int toAdd = (hasNumbers ? 0 : 1) + (hasLower ? 0 : 1) + (hasUpper ? 0 : 1) + (hasSpecial ? 0 : 1);

        return Math.max(6 - password.length(), 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();
    }
}