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.Scanner;

public class Solution {

    public static void main(String args[]) {
    Scanner scanner = new Scanner(System.in);
    int n = scanner.nextInt();
    int k = 0;
    for (int i = 0; i <= 512; i++) {
        k = Integer.parseInt(Integer.toBinaryString(i));
        if (n == k) {
        k = i;
        break;
        } else if (n < k) {
        k = i - 1;
        break;
        }
    }
    System.out.println(k);   
    }
}