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.IOException;
import java.io.InputStreamReader;

public class Round09ProblemC {

	public static void main(String[] args) {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		try {
			int[] param = parseIntegers(input.readLine());
			int n = param[0];
			System.out.println(solve(n));
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				input.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	private static int solve(int n) {
		int d = 0;
		int b = 0;
		while (true) {
			d = convert(b + 1);
			if (d <= n) {
				b++;
			} else {
				return b;
			}
		}
	}

	private static int convert(int n) {
		return Integer.parseInt(Integer.toBinaryString(n));
	}

	public static int[] parseIntegers(String line) {
		String[] strings = line.split("\\s");
		int[] numbers = new int[strings.length];
		for (int i = 0; i < strings.length; i++) {
			numbers[i] = Integer.parseInt(strings[i]);
		}
		return numbers;
	}
}
