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.io.File;
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner reader=new Scanner(System.in);
		int i=1, n=reader.nextInt();
		DFS a=new DFS(n);
		a.dfs(1);
		System.out.println(a.ans);
	}
}

class DFS
{
	int ans=0, n;
	DFS(int n)
	{
		this.n=n;
	}
	void dfs(int i)
	{
		if(i>n)
		{
			return;
		}
		else {
			this.ans++;
		}
		if(i*10<=n)
		{
			dfs(i*10);
		}
		if(i*10+1<=n)
		{
			dfs(i*10+1);
		}
	}
}