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 boredom {
	
	public static int no(int n) {
		String str= Integer.toBinaryString(n);
		int num = 0;
		for(int i =0; i<str.length(); i++) {
			num = num*10 + (str.charAt(i)-'0');
		}
		return num;
	}
	public static void main(String[] args) {
		
		Scanner s = new Scanner(System.in);
		int n = s.nextInt();
		int digit = (int) Math.log10(n);
		int ans = (int) (Math.pow(2, digit) )-1;
		ans++;
		boolean x = true;
		while(x) {
			if(no(ans) <= n) {
				ans++;
			}
			else
				x = false;
		}
		System.out.println(ans-1);
	}
}