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;

/**
 * 9C
 *
 * @author artyom
 */
public class HexadecimalsNumbers {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        char[] digits = sc.nextLine().toCharArray();
        int i = 0, n = digits.length;
        while (i < n) {
            if (digits[i] > '1') {
                break;
            }
            i++;
        }
        for (int j = i; j < n; j++) {
            digits[j] = '1';
        }
        System.out.println(Integer.parseInt(new String(digits), 2));
    }
}