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.*;
import java.io.*;
public class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		DataInputStream ab=new DataInputStream(System.in);
		String s,s1="";
		s=ab.readLine();
		int l=s.length();
		for(int i=0;i<l;i++)
		{
			if(s.charAt(i)-'0'>1)
			{
				for(int j=i;j<l;j++)
				{
					s1+='1';
				}
				break;
			}
			else
				s1+=s.charAt(i);
		}
		long ans=Integer.parseInt(s1,2);
		System.out.println(ans);
	}
}