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 Solution {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);

        int n = Integer.parseInt(s.next());
        int dec = 1;
        String binary = Integer.toBinaryString(dec);
        int res = 0;

        while (Integer.parseInt(binary) <= n) {
            res++;
            dec++;
            binary = Integer.toBinaryString(dec);
        }

        System.out.println(res);

        s.close();
    }
}