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

public class Solution {

    static Set<Character> numberSet = new HashSet<>();
    static Set<Character> lowerSet = new HashSet<>();
    static Set<Character> upperSet = new HashSet<>();
    static Set<Character> specialSet = new HashSet<>();
    
    static void buildCharSets(){
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
        
        for(int i = 0; i < numbers.length(); i++){
            numberSet.add(numbers.charAt(i));
        }
        for(int i = 0; i < lower_case.length(); i++){
            lowerSet.add(lower_case.charAt(i));
        }
        for(int i = 0; i < upper_case.length(); i++){
            upperSet.add(upper_case.charAt(i));
        }
        for(int i = 0; i < special_characters.length(); i++){
            specialSet.add(special_characters.charAt(i));
        }
        
        
        
    }
    
    static int minimumNumber(int n, String password) {
        // Return the minimum number of characters to make the password strong
        int numcount = 0;
        int lowerCount = 0;
        int upperCount = 0;
        int specialCount = 0;
        int weakness = 0;
        for(int i = 0; i < password.length(); i++){
            if(numberSet.contains(password.charAt(i)))
                numcount++;
            else if (lowerSet.contains(password.charAt(i)))
                lowerCount++;
            else if (upperSet.contains(password.charAt(i)))
                upperCount++;
            else
                specialCount++;
        }
        
        if (numcount < 1)
            weakness++;
        if (lowerCount < 1)
            weakness++;
        if (upperCount < 1)
            weakness++;
        if (specialCount < 1)
            weakness++;
        
        return Math.max((6-password.length()), weakness);
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String password = in.next();
        buildCharSets();
        int answer = minimumNumber(n, password);
        System.out.println(answer);
        in.close();
    }
}