import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    
    static final String numbers = "0123456789";
    static final String lower_case = "abcdefghijklmnopqrstuvwxyz";
    static final String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    static final String special_characters = "!@#$%^&*()-+";

    static int minimumNumber(int n, String password) {
        // Return the minimum number of characters to make the password strong
        char[] a = password.toCharArray();
        int typeCount = 0;
        boolean isNum = false, isUpper = false, isLower = false, isSpecial = false;
        for (char c: a) {
            if (numbers.indexOf(c) >= 0 && !isNum) {
                typeCount++;
                isNum = true;
            }
            if (lower_case.indexOf(c) >= 0 && !isLower) {
                typeCount++;
                isLower = true;
            }
            if (upper_case.indexOf(c) >= 0 && !isUpper) {
                typeCount++;
                isUpper = true;
            }
            if (special_characters.indexOf(c) >= 0 && !isSpecial) {
                typeCount++;
                isSpecial = true;
            }
            if (typeCount == 4){
                break;
            }
        }
        return Math.max(6 - n, 4 - typeCount);
    }

    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();
    }
}