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) {
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
        int countN = 0, countL = 0, countU = 0, countS = 0, count = 0;
        for(int i = 0; i < password.length(); i++) {
            if(numbers.contains(password.substring(i,i+1)))
               countN++;
            else if(lower_case.contains(password.substring(i,i+1)))
               countL++;
            else if(upper_case.contains(password.substring(i,i+1)))
               countU++;
            else if(special_characters.contains(password.substring(i,i+1)))
               countS++;
               }
        if(countN==0) count++;
        if(countL==0) count++;
        if(countU==0) count++;
        if(countS==0) count++;
        return Math.max(count, 6-password.length());
    }

    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();
    }
}