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 shashank
{
	public static void main(String args[])
	{
		Scanner s = new Scanner(System.in);
		String number = s.next();
		String largestBin = "";

		for(int i = 0; i < number.length(); i++)
		{
			int k = Integer.parseInt(Character.toString(number.charAt(i)));
			if(k > 1)
			{
				for(int j = i; j < number.length(); j++)
					largestBin += "1";
				break;
			}
			else if(k == 1)
				largestBin += "1";
			else
				largestBin += "0";
		}

		System.out.println(Integer.parseInt(largestBin, 2));
	}
}