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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class Binary
{
	// http://codeforces.com/problemset/problem/9/C
	
	public static void main(String[] args) throws NumberFormatException, IOException
	{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw = new PrintWriter(System.out);
		
		long N = Long.parseLong(br.readLine()); 
		int count = 1;
		int bin = 0;
		
		bin = Integer.parseInt(Integer.toBinaryString(count++));
		
		while(bin <= N){
			bin = Integer.parseInt(Integer.toBinaryString(count++));
		}
		
		pw.println(count-2);
		pw.close();
	}
}
