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.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class workspace {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Scanner scan = new Scanner(System.in);

		long n = scan.nextLong();
		long ans = 1;
		hexaNumbers(n, ans);
		System.out.println(count);
	}

	static int count = 0;

	public static void hexaNumbers(long n, long ans) {

		if (n < ans) {
			return;
		} else if (n >= ans) {
			count++;
			
		}
		
		hexaNumbers(n, ans*10 +1);
		hexaNumbers(n, ans*10);
		

		return;
	}
}