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.io.*;
import java.util.*;
import java.math.*;

public class P9C {

  public PrintWriter run() {
    long n = sc.nextLong();
    if (n == 1) {
      pw.println(1);
      return pw;
    }
    long z = 1;

    while (Long.valueOf(Long.toString(z, 2)) <= n) {
      z++;
    }

    pw.println(z - 1);

    return pw;
  }

  private Scanner sc = new Scanner(new BufferedInputStream(System.in));
  private PrintWriter pw = new PrintWriter(new BufferedOutputStream(System.out));

  public static void main(String... args) throws Exception {
    new P9C().run().close();
  }

}
