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 Main {

	public static void main(String[] args) {

		Scanner scn = new Scanner(System.in);

		long n = scn.nextLong();



		int ans = 0;

		for (int i = 1; i < (int) (Math.pow(2, 10)); i++) {

			long x = tobinary(i);

			if (x <= n) {
				ans++;
			} else {
				break;
			}

		}

		System.out.println(ans);
	}

	private static long tobinary(int i) {

		long ans = 0;

		long mult = 1;

		while (i != 0) {

			ans = ans + mult * (i % 2);
			i /= 2;
			mult*=10;
		}

		return ans;
	}

}
