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.util.*;


public class HexadecimalNumbers
{
	public Scanner in;
	public PrintWriter out;
	
	HexadecimalNumbers()
	{
		in = new Scanner(System.in);
		out = new PrintWriter(System.out);
	}
	
	HexadecimalNumbers(String i, String o) throws FileNotFoundException
	{
		in = new Scanner(new File(i));
		out = new PrintWriter(new File(o));
	}
	
	public void finalize()
	{
		out.flush();
		in.close();
		out.close();
	}
	
	public int toBinary(int n)
	{
		String s = "";
		
		while(n > 0)
		{
			s = n % 2 + s;
			n >>= 1;
		}
		
		return Integer.parseInt(s);
	}
	
	public void solve()
	{
		int n = in.nextInt(), c = 0;
		
		for(int i = 1; i < 1025; ++i)
		{
			int k = toBinary(i);
			
			if(k > n)
				break;
			
			++c;
		}
		
		System.out.println(c);
	}
	
	public static void main(String[] args)
	{
		HexadecimalNumbers t = new HexadecimalNumbers();
		t.solve();
		t.finalize();
	}
}

