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 = "!@#$%^&*()-+"; 
        char[] numbersArr = numbers.toCharArray();  
        //System.out.println(numbersArr[0]);
        int count = 0;
        int flag1 = 1;
        int flag2 = 1;
        int flag3 = 1;
        int flag4 = 1;
        for (char ch: lower_case.toCharArray())
        {
            if (password.contains("" + ch))    
            {
                flag1 = 0;
                break;
            }    
    
        }
        for (char ch: upper_case.toCharArray())
        {
            if (password.contains("" + ch))
                {
                    flag2 = 0;
                    break;
                }
        }
        for (char ch: special_characters.toCharArray())        
                {
                    if (password.contains("" + ch))
                        {
                            flag3 =0;
                    break;
                        }
                    
                    }
                
       for (char ch: numbers.toCharArray())         
                {
                    if (password.contains("" + ch))
                        {
                            flag4 =0;
                    break;
                        }
                }
        count = flag1+flag2+flag3+flag4;
      if (password.length() + count < 6 )
          return 6 - password.length();
          
         
        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();
    }
}