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 HexadecimalsNumbers {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        long input = scanner.nextLong();
        for(long i=1; i<=(1<<9)+1; i++) {
            String bin = Long.toBinaryString(i);
            long ii = Long.parseLong(bin);
            if(ii > input) {
                System.out.println(i-1);
                return;
            }
        }
    }
}
