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 digits_left = ((6 - n) > 0 ? (6 - n) : 0);
        boolean has_numbers = false;
        boolean has_lower_case = false;
        boolean has_upper_case = false;
        boolean has_special_characters = false;
        
        for (int i = 0; i < password.length(); i++) {
            if (!has_numbers && numbers.contains(Character.toString(password.charAt(i)))) {
                has_numbers = true;
            } else if (!has_lower_case && lower_case.contains(Character.toString(password.charAt(i)))) {
                has_lower_case = true;
            } else if (!has_upper_case && upper_case.contains(Character.toString(password.charAt(i)))) {
                has_upper_case = true;
            } else if (!has_special_characters && special_characters.contains(Character.toString(password.charAt(i)))) {
                has_special_characters = true;
            }
        }
        
        int types_left = (has_numbers ? 0 : 1) +
                         (has_lower_case ? 0 : 1) +
                         (has_upper_case ? 0 : 1) +
                         (has_special_characters ? 0 : 1);
        
        return (digits_left > types_left) ? digits_left : types_left;
    }

    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();
    }
}