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) {
        String L = "abcdefghijklmnopqrstuvuwxyz";
        String U = L.toUpperCase();
        String N = "0123456789";
        String X = "!@#$%^&*()-+";
        
        int count = 4;
        for (String s: new String[] { L, U, N, X })
            for (int i = 0; i < password.length(); i++)
                if (s.indexOf(password.charAt(i)) > -1) {
                    count--;
                    break;
                }
        
        if (password.length() < 6)
            count = Math.max(count, 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();
    }
}