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.Scanner;

public class CF9C {
	public static void main(String[] args) {
		try (Scanner sc = new Scanner(System.in)) {
			int n = sc.nextInt();
			int m = 0, ctr = 0;
			String b = "";
			for (int i=1; i<=512; i++) {
				b = Integer.toBinaryString(i);
				m = Integer.parseInt(b);
//				System.out.println(b+" -> "+m);
				if (m <= n)
					ctr++;
				else
					break;
			}
			System.out.println(ctr);
		}
	}
}

    	 	 					 	 		  	 					