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 HexadecimalNums {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int res = 0;
        int i = 0;
        while (n != 0) {
            int ld = (n % 10 > 0 || test(n / 10)) ? 1 : 0;
            n /= 10;

            res += (1 << i++) * ld;

        }
        System.out.println(res);
    }

    private static boolean test(int n) {
        while (n != 0) {
            if (n % 10 > 1)
                return true;
            n = n/10;
        }
        return false;
    }
}