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.io.*;
public class Hexadecimals_Numbers
{
	public static void main(String args[]) throws Exception
	{
		BufferedReader f=new BufferedReader(new InputStreamReader(System.in));
		// BufferedReader f=new BufferedReader(new FileReader("Hexadecimals_Numbers.in"));
		int num=Integer.parseInt(f.readLine());
		int counter=0;
		for(int x=1;x<1024;x++)
			if(Integer.parseInt(Integer.toBinaryString(x))<=num)
				counter++;
		System.out.println(counter);
	}
}