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 Hexadecimal {
    static Scanner key = new Scanner (System.in);
    public static void main (String args[]){
        int input = key.nextInt();
       String a = "1";
       int count = 0;
         while (true) {
             if (Integer.parseInt(a)<=input) {
            int binary = Integer.parseInt(a,2)+1;
            a = Integer.toBinaryString(binary);
            count++;
             } else {
                 break;
             }
         }
        System.out.println(count);
    }
        
}
