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) {
        Pattern p = Pattern.compile("(?<spec>[!@#$%^&*()\\-+]+)|(?<low>[a-z]+)|(?<high>[A-Z]+)|(?<dig>\\d+)");
        Matcher m = p.matcher(password);
        
        boolean[] set = new boolean[4];
        while (m.find()) {
            set[0] = set[0] || m.group("spec") != null;
            set[1] = set[1] || m.group("low") != null;
            set[2] = set[2] || m.group("high") != null;
            set[3] = set[3] || m.group("dig") != null;
        }
        
        int count = 4;
        for (int i = 0; i< 4; i++) {
            if (set[i]) count--;
        }
        
        if (password.length() >= 6) {
            return count;
        } else {
            int v = 6 - password.length();
            if (v >= count) {
                return v;
            } else {
                return count;
            }
        }
    }

    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();
    }
}