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 = "!@#$%^&*()-+";

        boolean num = false;
        boolean l = false;
        boolean u = false;
        boolean s = false;

        for (int i=0;i<n;i++) {

            char c = password.charAt(i);

            if (numbers.contains(c+"")) {
                num = true;
            }

            if (lower_case.contains(c+"")) {
                l = true;
            }

            if (upper_case.contains(c+"")) {
                u = true;
            }

            if (special_characters.contains(c+"")) {
                s = true;
            }

        }

        int ans = 0;
        if(!num){
            ans++;
        }

        if(!l){
            ans++;
        }

        if(!u){
            ans++;
        }

        if(!s){
            ans++;
        }

        if(ans+n<6){
            return 6 - n;
        }else
            return ans;
    }

    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();
    }
}