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 = "!@#$%^&*()-+";
        int a=0,b=0,c=0,d=0;
        
        for(int i=0;i<password.length();i++)
        {
            if(numbers.indexOf(password.charAt(i))>=0)
                a=1;
            else if(lower_case.indexOf(password.charAt(i))>=0)
                b=1;
            else if(upper_case.indexOf(password.charAt(i))>=0)
                c=1;
            else if(special_characters.indexOf(password.charAt(i))>=0)
                d=1;
            
                
        }
        
        
         if(password.length()+(4-a-b-c-d)>=6)
            return (4-a-b-c-d);
         
            return (6-password.length());
        
        
        
        
    }

    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();
    }
}