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 hexadecimalsNumbers
{
  public static void main(String[] args) 
  {
    Scanner br=new Scanner(System.in);
    int n=br.nextInt();
    int i=1,ans=0;
    while(true)
    {
    	if(Integer.parseInt(Integer.toBinaryString(i))>n)
    	{
    		break;
    	}
    	else
    	{
    		ans++;
    	}
   		i++;
 	}
  
    System.out.println(ans);
   
  }	
}