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 G {

	
	static int p, q, ans;
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		String s = in.nextLine();
		p = Integer.parseInt(s);
		q = s.length();		
		ans = 0; int m = 1;
		for (int i = 0; i < q - 1; i++) {
			ans += m;
			m = m * 2;
		}
		go(1, 1);
		System.out.println(ans);
	}
	private static void go(int pos, int cur) {
		if (pos == q) {
			if (cur <= p) ans++;
			return;
		}
		for (int i = 0; i < 2; i++) go(pos + 1, cur * 10 + i);
	}

}

  	 						  		  	 			  	