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 C0009_HexadecimalsNumbers {

	public static void main(String[] args) {
		InputReader in = new InputReader();
		int n = in.nextInt();
		
		int res = 0;
		for (int i=1; i<=512; i++) {
			String s = Integer.toBinaryString(i);
			int a = Integer.parseInt(s);
			if (a <= n)
				++res;
			else break;
		}
		
		System.out.println(res);
	}
	
	static class InputReader {
		public BufferedReader br;
		public StringTokenizer st;
		
		public InputReader() {
			st = null;
			br = new BufferedReader(new InputStreamReader(System.in));
		}
		
		public String next() {
			while (st == null || !st.hasMoreTokens()) {
				try {
					st= new StringTokenizer(br.readLine());
				}
				catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return st.nextToken();
		}
		
		public int nextInt() {
			return Integer.parseInt(next());
		}
	}
}
