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.*;
import java.io.*;
import java.math.BigInteger;

public class Tests{
	static Scanner in = new Scanner (System.in);
	//static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	static TreeSet <Integer> set = new TreeSet <Integer>();

	static PrintWriter out = new PrintWriter (System.out);
	
	public static void main (String []args) throws IOException {
		
	int n = in.nextInt();
	int count = 0;
	
	for(int i = 1 ; i<1024 ; i++){
		
		set.add(Integer.parseInt((Integer.toBinaryString(i))));
	}
	
	for(int i : set){
		if(i<=n){
			count++;
		}
	}
	

	/*for(int i : set){
		out.println(i);
	}
	*/
	out.println(count);
				
				
	    out.flush();
		out.close();
				
	}

	


	
}