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 = "!@#$%^&*()-+";

    static int minimumNumber(int n, String password) {
        boolean numbers = false;
        boolean lower_case = false;
        boolean upper_case = false;
        boolean special_characters = false;

        int count = 0;
        for (char c : password.toCharArray())
        {
            if(Solution.numbers.contains(String.valueOf(c)) && !numbers)
            {
                numbers = true;
                count++;
            }
            if(Solution.lower_case.contains(String.valueOf(c)) && !lower_case)
            {
                lower_case = true;
                count++;
            }
            if(Solution.upper_case.contains(String.valueOf(c)) && !upper_case)
            {
                upper_case = true;
                count++;
            }
            if(Solution.special_characters.contains(String.valueOf(c)) && !special_characters)
            {
                special_characters = true;
                count++;
            }
        }

        if(n < 6)
        {
            int charsLeft = 6 - n;
            charsLeft -= 4 - count;
            
            if(charsLeft > 0)
            {
                return 4 - count + charsLeft;
            } else
            {
                return 4 - count;
            }
        } else
        {
            return 4 - count;
        }
    }

    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();
    }
}