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

public class Main 
{
    public static void main(String[] argc)
    {
		Scanner cin=new Scanner(new BufferedInputStream(System.in));
		while(cin.hasNext()){
			String s=cin.next();
			int tp=s.length();
			int i,ans=0;
			for(i=0;i<tp;i++){
				if(s.charAt(i)=='1') ans=ans*2+1;
				else if(s.charAt(i)=='0') ans=ans*2;
				else break;
			}
			for(;i<tp;i++)
				ans=ans*2+1;
			System.out.println(ans);
		}
    }

}