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) {
        char[] ps = password.toCharArray();
       
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
        int faltan = 0;
       

        boolean[] existen = new boolean[4];

        for (int i = 0; i < ps.length; i++) {
            if (numbers.contains(String.valueOf(ps[i]))) {
                existen[0] = true;
            }

            if (lower_case.contains(String.valueOf(ps[i]))) {
                existen[1] = true;
            }

            if (upper_case.contains(String.valueOf(ps[i]))) {
                existen[2] = true;
            }

            if (special_characters.contains(String.valueOf(ps[i]))) {
                existen[3] = true;
            }
        }

        for (int i = 0; i < existen.length; i++) {
            if (!existen[i]) {
                faltan++;
            }
        }

        if(faltan+n>6){
            return faltan;
        } else{
            return faltan + (6-faltan-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();
    }
}