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 P009C {

    public static void main(String[] args) {
        Scanner inScanner = new Scanner(System.in);
        char[] chars = inScanner.next().toCharArray();
        int n = chars.length;
        boolean badFound = false;
        for (int i = 0; i < n; i++) {
            if (chars[i] > '1')
                badFound = true;
            if (badFound)
                chars[i] = '1';
        }
        System.out.println(Integer.parseInt(new String(chars), 2));
    }
}
