One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of n different natural numbers from 1 to n to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.

Input

Input data contains the only number n (1 ≤ n ≤ 109).

Output

Output the only number — answer to the problem.

Examples

Input

10


Output

2

Note

For n = 10 the answer includes numbers 1 and 10.

import java.util.*;

public class C
{
   public static void main(String[] args)
   {
      new C(new Scanner(System.in));
   }

   public C(Scanner in)
   {
      String s = in.next();
      long vi = Long.parseLong(s);
      
      int cnt = -1;
      for (int i=0; i<100000; i++)
      {
         String ss = Integer.toBinaryString(i);
         long vr = Long.parseLong(ss);
         if (vr > vi) break;
         cnt++;
      }

      System.out.println(cnt);
   }
}
