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.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class File1 {
	private static double dis(long x, long ux, long uy) {
		return Math.sqrt((ux - x) * (ux - x) + uy * uy);
	}
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int nd = 0;
		int a = n;
		ArrayList<Integer> dig = new ArrayList<Integer>();
		while(a>0){
			nd++;
			dig.add(a%10);
			a/=10;
		}
		int ans = 0;
		Collections.reverse(dig);
		for(int i=0;i<dig.size();i++){
			if(dig.get(i)>1){
				for(int j=i;j<dig.size();j++){
					ans = ans*2+1;
				}
				break;
			}
			else if(dig.get(i)==1)
				ans = ans*2+1;
			else
				ans = ans*2;
		}
		System.out.println(ans);
	}
}