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 {
//	static Scanner in; static int next() throws Exception {return in.nextInt();};
	static StreamTokenizer in; static int next() throws Exception {in.nextToken(); return (int) in.nval;}
//	static BufferedReader in;
	static PrintWriter out;

	public static void main(String[] args) throws Exception {
//		in = new Scanner(System.in);
		in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
//		in = new BufferedReader(new InputStreamReader(System.in));
		out = new PrintWriter(System.out);

		int n = next();
		int count = 0;

		for (int mask = 1; mask < 1023; mask++) {
			int t = 1;
			int sum = 0;
			for (int i = 0; i < 10; i++) {
				if ((mask & (1 << i)) != 0) sum += t;
				t *= 10;
			}
			if (sum <= n) count++;
		}

		out.println(count);

		out.close();
	}
}