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

public class Solution {
    private static final String SPECIAL_CHARS = "!@#$%^&*()-+";

    static int minimumNumber(int n, String password) {
        // Return the minimum number of characters to make the password strong
        int required = 4;
        
        boolean hasLowerCase = false;
        boolean hasUpperCase = false;
        boolean hasDigit = false;
        boolean hasSpecialChar = false;
        
        for(int i = 0; i < n; i++) {
            Character c = password.charAt(i);
            if(!hasLowerCase && Character.isLowerCase(c)) {
                required--;
                hasLowerCase = true;
            } else if(!hasUpperCase && Character.isUpperCase(c)) {
                required--;
                hasUpperCase = true;
            } else if(!hasDigit && Character.isDigit(c)) {
                required--;
                hasDigit = true;
            } else if(!hasSpecialChar && SPECIAL_CHARS.indexOf(c) != -1) {
                required--;
                hasSpecialChar = true;
            }
        }
        
        if(n < 6) {
            required = Math.max(6 - n, required);
        }
        
        return required;
    }

    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();
    }
}