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 Main {
	static long ans = 0, n;
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		n = in.nextLong();
		dfs(1);
		System.out.println(ans);
	}
	public static void dfs( long num ) {
		if( num > n )
			return;
		if( num <= n ) {
			ans++;
		}
		dfs(num * 10 + 1);
		dfs(num * 10 + 0);
	}
}
