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) {
        // Return the minimum number of characters to make the password strong
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
        
        boolean[] checks = new boolean[4];
                          
        for(int i = 0; i < n; i++) {
            String character = password.substring(i, i+1);
            if(numbers.contains(character))
            {
                checks[0] = true;
            }
            if(lower_case.contains(character))
            {
                checks[1] = true;
            }
            if(upper_case.contains(character))
            {
                checks[2] = true;
            }
            if(special_characters.contains(character))
            {
                checks[3] = true;
            }
        }
        
        int neededChars = 0;
        
        for(int i = 0; i < 4; i++ )
        {
            if(checks[i] == false)
            {
                neededChars++;
            }
        }
        
        if (n < 6 )
        {
            if(neededChars > 6 - n)
            {
                return neededChars;
            }
            return 6 - n;
        }
        else
        {
            return neededChars;
        }
    }

    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();
    }
}