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 Solution {
	public static void main(String[] args){
		Solution solution = new Solution();
		solution.solve();
	}

	private void solve(){
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int[] a = new int[512];
		for (int i = 0; i < 512; ++i) a[i] = Integer.parseInt(Integer.toBinaryString(i+1));
		for (int i = 0; i < 512; ++i) {
			if (a[i] > n) {
				System.out.println(i);
				return;
			}
		}
		System.out.println(512);
	}
}
