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.Scanner;

/**
 * 
 */

/**
 * @author dr. Jafar
 *
 */
public class P9C {
	
	 public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		long a = in.nextLong();
		int res = 0;
		for(int i=1; Integer.parseInt(Integer.toBinaryString(i)) <= a; i++ )
			res++;
		System.out.println(res);
	 }

}
