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) {
        String numbers="0123456789";
        String big_alpha="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String small_alpha="abcdefghijklmnopqrstuvwxyz";
        String symbols="!@#$%^&*()-+";
        boolean[] arr=new boolean[4];
                    int req_char=0;
        for(int i=0;i<password.length();i++)
        {
            if(numbers.contains(String.valueOf(password.charAt(i)))) arr[0]=true;
            if(big_alpha.contains(String.valueOf(password.charAt(i)))) arr[1]=true;
            if(small_alpha.contains(String.valueOf(password.charAt(i)))) arr[2]=true;
            if(symbols.contains(String.valueOf(password.charAt(i)))) arr[3]=true;
        }
        for(int i=0;i<4;i++)
        { 
           if(arr[i]==false) req_char++;
        }
        if(req_char==0&&n>=6) return 0;
        if(req_char!=0 )
        {
            if(password.length()>=6) return req_char;
            if(password.length()<6) 
            {
             if((6-password.length())>=req_char) return (6-password.length());     
              else return req_char;
            }
        }
        else
        {
            if(password.length()<6) 
            {
             return (6-password.length());     
            }
            else return 0;
        }
 return 0;       // Return the minimum number of characters to make the password strong
    }

    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();
    }
}