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.util.*;
import java.io.*;

public class GenericProblem
{
	/*
	 * This FastReader code is taken from GeeksForGeeks.com
	 * https://www.geeksforgeeks.org/fast-io-in-java-in-competitive-programming/
	 * 
	 * The article was written by Rishabh Mahrsee
	 */
	public static class FastReader 
    { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() 
        { 
            br = new BufferedReader(new
                     InputStreamReader(System.in)); 
        } 
  
        String next() 
        { 
            while (st == null || !st.hasMoreElements()) 
            { 
                try
                { 
                    st = new StringTokenizer(br.readLine()); 
                } 
                catch (IOException  e) 
                { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() 
        { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() 
        { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() 
        { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() 
        { 
            String str = ""; 
            try
            { 
                str = br.readLine(); 
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    }

	public static void main(String[] args)
	{
		FastReader file = new FastReader();
		PrintWriter out = new PrintWriter(System.out);

		// Can only be binary numbers from 1-512
		String[] bin = new String[513];
		
		for (int i = 1; i <= 513; i++)
		{
			bin[i - 1] = Integer.toBinaryString(i);
		}
		
		int n = file.nextInt();
		
		// Index of first base 10 number is the answer
		int answer = -1;
		for (int i = 0; i < bin.length; i++)
		{
			if (Integer.parseInt(bin[i]) > n)
			{
				answer = i;
				break;
			}
		}
		out.println(answer);
		
		out.close();
	}
}
