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) {
        boolean length=false,digit=false,lowercase=false,uppercase=false,special=false;
        
        String numbers = "0123456789",lower_case = "abcdefghijklmnopqrstuvwxyz",upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ",special_characters = "!@#$%^&*()-+";
        if (password.length()<6)
            length=false;
        else
            length=true;
        for (int i=0;i<password.length();i++)
        {

            for (int j=0;j<numbers.length();j++)
            {
                if (password.charAt(i)==numbers.charAt(j))
                    digit=true;
            }
            
            for (int j=0;j<lower_case.length();j++)
            {
                if (password.charAt(i)==lower_case.charAt(j))
                    lowercase=true;
            }
            
            for (int j=0;j<upper_case.length();j++)
            {
                if (password.charAt(i)==upper_case.charAt(j))
                    uppercase=true;
            }
            
            for (int j=0;j<special_characters.length();j++)
            {
                if (password.charAt(i)==special_characters.charAt(j))
                    special=true;
            }
            
        }
        int count=0;
            if (!digit) count++;
            if (!lowercase) count++;
            if (!uppercase) count++;
            if (!special) count++;
            if (!length)
            {
                if ((6-password.length())>count)
                    return 6-password.length();
            }
            return 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();
    }
}