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 P009C {
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        
        String n = in.next();

        System.out.println(under(new boolean[n.length()], 0, Integer.parseInt(n))-1);
    }
    
    public static long under(boolean[] vals, int i, int N)
    {
        if (i == vals.length)
        {
            String temp = "";
            for (int j = 0; j < vals.length; ++j)
                if (vals[j]) temp += "1";
                else temp += "0";

            if (Integer.parseInt(temp) <= N) return 1;
            else return 0;
        }
        
        long ans = 0;
        vals[i] = false;
        ans += under(vals, i+1, N);
        vals[i] = true;
        ans += under(vals, i+1, N);
        
        return ans;
    }
}
