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.ArrayList;
import java.util.List;
import java.util.Scanner;

public class C {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		List<Integer> l = new ArrayList<Integer>();
		for(int i=1;i<=1<<9;i++){
		    l.add(Integer.valueOf(Integer.toBinaryString(i)));
		}
		while(s.hasNext()) {
		    int r = 0;
		    int n = s.nextInt();
		    for(int z : l) {
		        if (z <= n) {
		            ++r;
		        }
		    }
		    System.out.println(r);
		}
		}

}
