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
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
        int res = 6 - n;
        boolean d = false;
        boolean l = false;
        boolean u = false;
        boolean s = false;
        for (int i = 0; i < password.length(); i++) {
            char cur = password.charAt(i);
            if (d == false && cur >= 48 && cur <= 57) {
                d = true;
            }
            if (l == false && cur >= 65 && cur <= 90) {
                l = true;
            }
            if (u == false && cur >= 97 && cur <= 122) {
                u = true;
            }
            if (s == false && special_characters.indexOf(cur) >= 0) {
                s = true;
            }
        }
        int temp = 0;
        if (d == false) {
            temp++;
        }
        if (l == false) {
            temp++;
        }
        if (u == false) {
            temp++;
        }
        if (s == false) {
            temp++;
        }
        return Math.max(temp, res);
    }

    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();
    }
}