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.util.ArrayList;

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

        int n = Integer.parseInt(in.readLine());

        ArrayList<Integer> number = new ArrayList<Integer>();

        number.add(1);

        int cnt = 0;
        while (toNumber(number) <= n) {
            cnt++;
            number.set(0, number.get(0) + 1);
            for (int j = 0; number.get(j) > 1; j++) {
                number.set(j, 0);

                if (j + 1 == number.size()) {
                    number.add(1);
                } else {
                    number.set(j + 1, number.get(j + 1) + 1);
                }
            }
        }

        System.out.println(cnt);

        in.close();
    }

    private static int toNumber(ArrayList<Integer> number) {
        int result = 0;
        for (int i = 0; i < number.size(); i++) {
            result += Math.pow(10, i) * number.get(i);
        }

        return result;
    }
}
