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;
import java.util.Locale;
import java.util.StringTokenizer;

public class Main {

	void solve() throws IOException {
		int n = nextInt();
		long[] dp = new long[1 << 10 + 1];
		for (Integer i = 1; i <= 1 << 10; i++) {
			dp[i] = Long.parseLong(Long.toBinaryString(i));
		}
		int k = 0;
		boolean b = true;
		for (int i = 1; i <= 1 << 10 && b; i++) {
			if( dp[i]<=n ){
				k++;
			}else {
				b = false;
			}
		}
		out.println(k);
	}

	private BufferedReader in;
	private PrintWriter out;
	private StringTokenizer st;

	Main() throws IOException {
		Locale.setDefault(Locale.US);
		in = new BufferedReader(new InputStreamReader(System.in));
		out = new PrintWriter(System.out);
		eat("");
		solve();
		in.close();
		out.close();
	}

	private void eat(String str) {
		st = new StringTokenizer(str);
	}

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

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

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

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

	public static void main(String[] args) throws IOException {
		new Main();
	}
}