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 Main {
	static int count = 0;
	static int n;
	static int function(int m) {
		if(m>n) {
			return 0;
		}
		count ++;
		function(m*10);
		function(m*10+1);
		return count;
	}
	public static void main(String[] args) {
		Scanner cin = new Scanner(System.in);
		n = cin.nextInt();
		System.out.println(function(1));
	}
}
