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.*;
import java.util.*;

public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String s = in.readLine();
        for (int i = 0; i < s.length(); i++) {
            if (!(s.substring(i, i + 1).equals("0")) && !(s.substring(i, i + 1).equals("1"))) {
                int len = s.length();
                s = s.substring(0, i);
                for (int j = 0; j < len - i; j++) {
                    s += "1";
                }
            }
        }
        int n = Integer.parseInt(s);
        int mul = 1; int ans = 0;
        while(n > 0) {
            ans += (n % 10) * mul; n /= 10;
            mul *= 2;
        }
        System.out.println(ans);
    }
}