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.Arrays;
import java.util.Scanner;

public class Main {

    static int n,cnt=0;

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        n = in.nextInt();
        dfs(1);
        System.out.println(cnt);
    }

    private static void dfs(int i) {
        if (i>n) return;
        cnt ++;
        dfs(i*10);
        dfs(i*10+1);
    }

}
 	  				 	  					  	 			 		