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.InputStreamReader;
import java.util.Scanner;

public class CodeForces_Hexadecimal_Numbers {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scan = new Scanner(new InputStreamReader(System.in));
		int n = scan.nextInt();
		scan.close();
		int num = 1,i = 1;
		for(i=1;num <= n;i++){
			String s = Integer.toBinaryString(i);
			num = Integer.parseInt(s);
		}
		System.out.println(i-2);
	}

}
