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.*;

public class CF9C {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] aa = new int[10];
		int d = 0;
		while (n > 0) {
			aa[d++] = n % 10;
			n /= 10;
		}
		int a2 = 0;
		int i2 = 0;
		for (int i = 0; i < d; i++)
			if (aa[i] > a2 || aa[i] >= 2) {
				a2 = aa[i];
				i2 = i;
			}
		int cnt = a2 == 1 ? 1 << i2 : (1 << i2 + 1) - 1;
		for (int i = i2 + 1; i < d; i++)
			if (aa[i] > 0)
				cnt += 1 << i;
		System.out.println(cnt);
	}
}
