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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;

/**
 * Created by James on 3/19/2015.
 */
public class Driver {
    public static void main(String [] args) throws IOException {
        BufferedReader scanner = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);

        int N = Integer.parseInt(scanner.readLine()), count = 1, answer = 0, bin = Integer.parseInt(Integer.toBinaryString(count));

        while (bin <= N) {
            answer++;
            bin = Integer.parseInt(Integer.toBinaryString(++count));
        }

        out.println(answer);

        out.close();
    }
}