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) {
        boolean hasDigit = false;
        boolean lowerCase = false;
        boolean upperCase = false;
        boolean special = false;
        
        String spe = "!@#$%^&*()-+";
        for (int i = 0; i < n; i++) {
            char c = password.charAt(i);
            if (Character.isDigit(c)) {
                hasDigit = true;
            } else if (c >= 'a' && c <= 'z') {
                lowerCase = true;
            } else if (c >= 'A' && c <= 'Z') {
                upperCase = true;
            } else if (spe.contains("" + c)) {
                special = true;
            }
        }
        int res = 0;
        if (!hasDigit) res++;
        if (!lowerCase) res++;
        if (!upperCase) res++;
        if (!special) res++;
        return Math.max(res, 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();
    }
}