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.Math.*;
public class Main
{
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		String s=sc.nextLine();
		double sum=0;
		String reverse="";
		for (int i = s.length() - 1 ; i >= 0 ; i--)
		{
		    reverse = reverse + s. charAt(i);
		}
		if(s.charAt(0)-'1'==0)
		{
		for(int i=0;i<reverse.length();i++)
		{
		    if(reverse.charAt(i)=='1')
		    {
		        double d=(double)i;
		        sum=sum+Math.pow(2,d);
		        
		    }
		    else if(reverse.charAt(i)-'0'>1)
		    {
		        sum=0;
		        for(int j=0;j<=i;j++)
		        {
		        double d=(double)j;
		        sum=sum+Math.pow(2,d);
		        }
		    }
		}
		}
		else
		{
		    
		   for(int i=0;i<reverse.length();i++)
		{
		    
		        double d=(double)i;
		        sum=sum+Math.pow(2,d);
		        
		    
		} 
		}
		System.out.println((int)sum);
	    
	}
}
