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) {
        // Return the minimum number of characters to make the password strong
        
        if(n <= 2){
            return 6-n;
        }
        
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
            
        boolean num = false;
        boolean lower = false;
        boolean upper = false;
        boolean special = false;
        for(int i=0; i<password.length(); i++){
            char c = password.charAt(i);
            if(numbers.indexOf(c) != -1){
                num = true;
            }
            if(lower_case.indexOf(c) != -1){
                lower = true;
            }
            if(upper_case.indexOf(c) != -1){
                upper = true;
            }
            if(special_characters.indexOf(c) != -1){
                special = true;
            }
        }
        
        int miss = 0;
        if(!num) miss++;
        if(!lower) miss++;
        if(!upper) miss++;
        if(!special) miss++;
        
        return Math.max(6-n, miss);
        
    }

    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();
    }
}