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 HexadecimalNumbers {

    

    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        Queue Q = new LinkedList();

        int a = in.nextInt();
        int res = 0;
        Q.add(1);

        Object b = Q.poll();
        while (b != null){
            int x = Integer.parseInt(b.toString());
            if (x > a) break;

            res++;
            Q.add(x * 10);
            Q.add(x * 10 + 1);

            b = Q.poll();
        }

        System.out.println(res);
    }
}
