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;

public class hexaDecimalNumbers {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int length = String.valueOf(n).length();
		int loaded = (int) Math.pow(2, length - 1) - 1;
		int start = Integer.valueOf(String.valueOf((int) Math.pow(10, length - 1)), 2);
		for (int i = start;; i++, loaded++) {
			if (Integer.parseInt(Integer.toBinaryString(i)) > n)
				break;
		}
		System.out.println(loaded);
	}
}
