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

public class Solution {

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

    static int minimumNumber(int n, String password) {
                // Return the minimum number of characters to make the password strong
        //if (n<6)
//           return 6-n;
        // at least one digit, lowercase, uppercase, special          
        int numberOfDigitsFound = 0;
        int numberOfLowerFound = 0;
        int numberOfUpperFound = 0;
        int numberOfSpecialFound = 0;
        for (int i=0; i<password.length(); i++) {
            char c = password.charAt(i);
            if (numbers.indexOf(c)>=0)
                numberOfDigitsFound++;
            if (lower_case.indexOf(c)>=0)
                numberOfLowerFound++;
            if (upper_case.indexOf(c)>=0)
                numberOfUpperFound++;
            if (special_characters.indexOf(c)>=0)
                numberOfSpecialFound++;
        }
        int totalNeeded = 0;
        if (numberOfDigitsFound == 0)
            totalNeeded++;
        if (numberOfLowerFound == 0)
            totalNeeded++;
        if (numberOfUpperFound == 0)
            totalNeeded++;
        if (numberOfSpecialFound == 0)
            totalNeeded++;

        if (n>=6)
            return totalNeeded;
        else if (6-n > totalNeeded)
            return 6-n;
        else
            return totalNeeded;
    }

    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();
    }
}