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 R = 4;
        String[] req = new String[R];
        req[0] = numbers;
        req[1] = lower_case;
        req[2] = upper_case;
        req[3] = special_characters;
        boolean[] satisfy = new boolean[R];
        for (int i = 0; i < n; i++) {
            char c = password.charAt(i);
            for (int j = 0; j < R; j++) {
                if (satisfy[j]) continue;
                
                if (req[j].indexOf(c) >= 0) {
                    satisfy[j] = true;
                    break;
                }
            }
        }
        
        int cnt = 0;
        for (boolean sa : satisfy)
            if (!sa) cnt++;
        return Math.max(cnt, 6 - n);
    }

    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();
    }
}