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.*;
import java.math.*;

public class R09C implements Runnable {
    BufferedReader in;
    StringTokenizer st;
    PrintWriter out;

    public void solve() throws IOException {
        int n = nextInt();

        char[] s = Integer.toString(n).toCharArray();
        int res = 0;

        int[] p = new int[10];
        for (int i = 0; i < 10; ++i) {
            p[i] = (1 << i);
        }

        for (int i = 0; i < s.length - 1; ++i) {
            res += p[i];
        }

        if (s[0] > '1') {
            res += (1 << (s.length - 1));
        } else {
            res += 1;
            boolean was = false;
            for (int i = 1; i < s.length; ++i) {
                int v = s.length - i - 1;
                if (s[i] > '1') {
                    was = true;
                }
                if ((s[i] == '1') || was) {
                    res += p[v];
                }
            }
        }

        System.out.println(res);
    }

    public void run() {
        try {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
            st = new StringTokenizer("");
            solve();
            out.close();
            in.close();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private String next() throws IOException {
        while (!st.hasMoreTokens()) {
            String line = in.readLine();
            if (line == null) {
                return null;
            }
            st = new StringTokenizer(line);
        }
        return st.nextToken();
    }

    private int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    private long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    private double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }

    private BigInteger nextBigInteger() throws IOException {
        return new BigInteger(next());
    }

    public static void main(String[] args) {
        Locale.setDefault(Locale.US);
        new Thread(new R09C()).start();
    }
}
