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 HexaRecursive {
	public static int calcu(long n) {
		if (n == 0)
			return 0;
		if (n <= 9) {
			return 1;
		} else {
			String s = String.valueOf(n);
			String num = "";
			for (int i = 0; i < s.length(); i++)
				num = num + "1";
			String constant = "";
			for (int i = 0; i < s.length() - 1; i++) {
				constant = constant + "0";
			}
			constant = "1" + constant;
			long oneAndZeroes = Long.parseLong(constant);
			long allOnes = Long.parseLong(num);
			if (allOnes <= n)
				return (int) (Math.pow(2, s.length())
						- Math.pow(2, s.length() - 1) + calcu(allOnes
						- oneAndZeroes));
			else
				return (int) (Math.pow(2, s.length())
						- Math.pow(2, s.length() - 1) + calcu(n - oneAndZeroes));
		}
	}

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		long x = scan.nextLong();
		System.out.println(calcu(x));
	}
}