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;

// Code Forces.. Recursion sessoion HW 
public class HexadecimalNumbers {

    public static int number(String s)
    {
        if(s.length() == 1)
        {
            if(s.charAt(0) == '0')
                return 1;
            else
                return 2;
        }
        else
            if(s.charAt(0)=='0')
                return number(s.substring(1));
            else if(s.charAt(0)=='1')
                return (int)Math.pow(2, s.length()-1)+number(s.substring(1));
            else 
                return (int)Math.pow(2, s.length());
                
    }
    
    public static int getNumber(long n)
    {
        return number(n+"");
    }
    
    public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    System.out.println(getNumber(scan.nextInt())-1);
    
    }

}