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 sample {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String n = in.next();
        int nn = Integer.parseInt(n);
        int l = n.length();
        int cnt = 0;
        for (int i = 0; i < l - 1; i++) {
            cnt += 1 << i;
        }
        int max = 1;
        for (int i = 1; i < l; i++) {
            max += Math.pow(10, i);
        }
        int i = (int) Math.pow(10, l - 1);
        for (; i <= max && i <= nn; i++) {
            if (isB(i))
                cnt++;
        }

        System.out.println(cnt);
    }

    public static boolean isB(int i) {
        while (i != 0) {
            if ((i % 10) > 1)
                return false;
            i /= 10;
        }
        return true;
    }
}