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.*;



public class Q5 {
   
    public static void main(String[] args) throws IOException{
         BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
         PrintWriter writer=new PrintWriter(System.out);
         String s=br.readLine();
         int ans=0;
         for(int i=1;i<=1023;i++)
         {
             String b="";
             int n=i;
             while(n>0)
             {
                 b=(n%2)+b;
                 n=n/2;
             }
             if(b.length()<s.length())
              ans++;
             else if(b.length()==s.length())
             {
                 if(s.compareTo(b)>=0)
                  ans++;
             }
         }
         writer.println(ans);
         writer.flush();
    }
}
