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 Hexadecimal_Numbers {

	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		
		int n=sc.nextInt();
		long arr[]=new long[1025];
		for(int i=1;i<1025;i++)
		{
			String s=Long.toBinaryString(i);
			arr[i]=Long.parseLong(s);
		}
			
		long ans=0;
		for(int i=1;i<1025;i++)
		{
			if(arr[i]<=n)
				ans=i;
		}
		System.out.println(ans);
		
sc.close();
	}

}
