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 Contact{
    public static void main(String args[]){
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int count = 0;
        int c = 2;
        int bin = Integer.parseInt(Integer.toString(1, 2));
        while(n>=bin){
            count++;
            bin = Integer.parseInt(Integer.toString(c,2));
            c++;
        }
        System.out.println(count);
    }
}