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.*;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		int n = s.nextInt();
		
		
		
		Queue<Integer> queue = new LinkedList<>();
		queue.add(1);
		int count = 0;
		while(!queue.isEmpty()){
			int temp = queue.poll();
			
			if(temp<=n){
				count++;
			}
			
			if(temp>n){
				break;
			}
			
			int n1 = temp*10;
			int n2 = temp*10+1;
			
			queue.add(n1);
			queue.add(n2);
			
			
		}
		
		System.out.println(count);

	}

}