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 CodeForces_9C {
	
	public static void main(String[] args)
	{
		Scanner scan= new Scanner(System.in);
		char[] charN = scan.nextLine().toCharArray();
		int cont = 0;
		for (int i=0; i<charN.length; i++)
			if (charN[i]<='1') cont += (charN[i]-'0') * Math.pow(2, charN.length-i-1);
			else {cont += Math.pow(2, charN.length-i)-1; break;}
		System.out.print(cont);
		scan.close();
	}
}
