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.InputStreamReader;
import java.util.LinkedList;


public class HexaDecimalNumbers {
	public static void main(String[] args) throws Exception {
		// TODO Auto-generated method stub
		BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
		String s=r.readLine();
		
		
		int n=new Integer(s);
		LinkedList<String> q=new LinkedList<String>();
		q.add("1");
		int c=0;
		while(!q.isEmpty()){
			String str=q.remove();
			if(Integer.parseInt(str)<=n){
				c++;
			}
			else 
				break;
			q.add(str+"0");
			q.add(str+"1");
		}
		System.out.println(c);
	}
}
