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

public class Solution {
    
    private static String numbers = "0123456789";
    private static String lower_case = "abcdefghijklmnopqrstuvwxyz";
    private static String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    private static String special_characters = "!@#$%^&*()-+";
    
    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();
    }
    
    public static int minimumNumber(int n, String password) {
        int minNumberOfCharacters = 6-password.length();
        int speacialNeeds = 0;
        if(!containsOneChar(password,numbers)) {
            speacialNeeds++;
        }
        if(!containsOneChar(password,lower_case)) {
            speacialNeeds++;
        }
        if(!containsOneChar(password,upper_case)) {
            speacialNeeds++;
        }
        if(!containsOneChar(password,special_characters)) {
            speacialNeeds++;
        }
        
        return Math.max(minNumberOfCharacters,speacialNeeds);
    }
    
    public static boolean containsOneChar(String password, String where) {
        for(int i=0;i<password.length();i++) {
            if(where.contains(""+password.charAt(i))) {
                return true;
            }
        }
        return false;
    }
        
}