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 C9 {

    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            String n = scanner.nextLine();
            StringBuilder formattedNumber = new StringBuilder();
            boolean continueOne = false;

            for (char ch : n.toCharArray()) {
                int digit = ch - 48;
                if (continueOne) {
                    formattedNumber.append(1);
                } else if (digit > 1) {
                    continueOne = true;
                    formattedNumber.append(1);
                } else {
                    formattedNumber.append(Math.min(digit, 1));
                }
            }

            System.out.println(Integer.valueOf(formattedNumber.toString(), 2));
        }
    }

}
