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 i,j;
        int req=4,found1=0,found2=0,found3=0,found4=0;
        for(i=0;i<n;i++)
        {
            if(found1==0)
            {
        	for(j=0;j<numbers.length();j++)
            {
            	if(password.charAt(i)==numbers.charAt(j))
                {
                	req--;
                	found1++;
                	break;
                }
            }
            }
            if(found2==0)
            {
            for(j=0;j<lower_case.length();j++)
            {
            	 if(password.charAt(i)==lower_case.charAt(j))
                 {
                 	req--;
                 	found2++;
                 	break;
                 }
            }
            }
            if(found3==0)
            {
            for(j=0;j<upper_case.length();j++)
            {
            	if(password.charAt(i)==upper_case.charAt(j))
                {
                	req--;
                	found3++;
                	break;
                }

            }
            }
            if(found4==0)
            {
            for(j=0;j<special_characters.length();j++)
            {
            	if(password.charAt(i)==special_characters.charAt(j))
                {
                	req--;
                	found4++;
                	break;
                }
            }
            }
        }
       // System.out.println(req);
      //  System.out.println(n+req);
        if((n+req)<6)
        {
        	req=6-n;
        }
        else
        {
        	req=req;
        }
        return req;
    }

    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();
    }
}