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

public class Solution {
    static String numbers = "0123456789";
    static String lower_case = "abcdefghijklmnopqrstuvwxyz";
    static String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    static String special_characters = "!@#$%^&*()-+";
        
    static int minimumNumber(int n, String password) {
        // Return the minimum number of characters to make the password strong
        int res = 0;
        int countNum = 0;
        int countLow = 0;
        int countUp = 0;
        int countSpec = 0;
        for (int i = 0; i< password.length(); i++ ){
            if (numbers.indexOf(password.charAt(i))>=0)
                countNum=1;
            else if (lower_case.indexOf(password.charAt(i))>=0)
                countLow=1;
            else if (upper_case.indexOf(password.charAt(i))>=0)
                countUp=1;
            else if (special_characters.indexOf(password.charAt(i))>=0)
                countSpec=1;
        }
        int need =  4 - (countNum + countLow+ countUp + countSpec);
        res = 6  - password.length() + need;
        if (password.length()<6){
            /*if ()
                return 6  - password.length();
            else
                return ;*/
            return Math.max(6-password.length(), need);
        }
        else
            return need;
    }

    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();
    }
}