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 {

    Scanner in;
    PrintWriter out;

    int counter = 0;
    char chars[] = new char[10];

    String tString() {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < chars.length; i++) {
            sb.append(chars[i]);
        }
        return sb.toString();
    }

    void gen(long n, int pos) {
        if (Integer.parseInt(tString()) > n) {
            counter--;
        } else if (pos >= 0) {
            chars[pos] = '1';
            counter++;
            gen(n, pos - 1);
            chars[pos] = '0';
            // counter++;
            gen(n, pos - 1);

        }
    }

    void solve() {
        String line = in.nextLine();
        long n = Long.valueOf(line);
        chars = new char[line.length()];
        Arrays.fill(chars, '0');
        gen(n, chars.length - 1);
        out.println(counter);
    }

    void run() {
        in = new Scanner(System.in);
        out = new PrintWriter(System.out);
        try {
            solve();
        } finally {
            out.close();
        }
    }

    public static void main(String[] args) {
        new Main().run();

    }
}
