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 HexadecimalsNumbers9 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int count = 0;
        int max = (1 << 10) ;
        for (int i = 1; i <= max; i++) {
            int num = 0;
            int rem = i;
            int mul = 1;
            while (rem > 0) {
                num += (mul * (rem & 1));
                rem >>= 1;
                mul *= 10;
            }
            if (num <= n) {
                count++;
            } else
                break;
        }
        System.out.println(count);
    }

}
