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.BufferedReader;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class A {

	private Set<Long> set;
	private int n;

	private void work() {
		Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(
				System.in)));
		set = new HashSet<Long>();
		n = sc.nextInt();
		go(1);
		System.out.println(set.size());
	}

	private void go(long x) {
		if (x > n)
			return;
		set.add(x);
		go(10 * x);
		go(10 * x + 1);
	}

	public static void main(String[] args) {
		new A().work();
	}

}
