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.*;
import java.lang.*;

public class Homgo
{

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

		
		
		
		String s=new String ();
		String s1=new String ();
		
		 s=in.next();
		int n=Integer.parseInt(s);
		
		
		int n1;	
		
		int left=1;
		int right=1000;
		int mid=(left+right)/2;
		
		while (right-left>1)
			{
			mid=(left+right)/2;
			s1=Integer.toBinaryString(mid);
			n1=Integer.parseInt(s1);
			if (n1>n)	right=mid;
			else left=mid;

			
			
			
			}
				
		System.out.print(left);
		}

	public static int toBinary(int n)
	{
	
	
	int result=0;
	
	while (n>0)
	{
	result=result*10+n%2;
	
	n/=2;
	}
	
	return result;
	}
		

}