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 problem9C {
	public static void main(String[] args) {
		Scanner console = new Scanner(System.in);
		int n = console.nextInt();
		int cur = 1;
		int res = 0;
		StringBuilder conv;
		int i;
		int temp;
		while (true) {
			conv = new StringBuilder();
    		i = 0;
    		temp = cur;
    		while (temp > 0){
        		conv.append(temp%2);
        		i++;
        		temp = temp/2;
    		}
    		if (Integer.parseInt(conv.reverse().toString()) <= n) {
    			res++;
    			cur++;
    		}
    		else {
    			break;
    		}
		}
		System.out.println(res);
	}
}