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.BufferedInputStream;
import java.util.Scanner;

/**
 * Created by jizhe on 2016/1/14.
 */
public class HexadecimalsNumbers {
    public static void main(String[] args) {
        Scanner in = new Scanner(new BufferedInputStream(System.in));

        int N = in.nextInt();

        int i = 1, count = 0;
        int number = Integer.parseInt(Integer.toString(i, 2));
        while( number <= N )
        {
            count++;
            //System.out.printf("%s\n", Integer.toString(i, 2));
            i++;
            number = Integer.parseInt(Integer.toString(i, 2));
        }

        System.out.printf("%d\n", count);
    }
}
