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 {

    /**
     * @param args
     * @throws IOException 
     */
    public static long nextBit(long x)
    {
        String xx=String.valueOf(x);
        String res="";
        boolean check=true;
        for (int i=xx.length()-1; i>=0; i--)
        {
            if (!check) res=xx.charAt(i)+res;
            else if (xx.charAt(i)=='0') {res="1"+res;  check=false; }
            else if (xx.charAt(i)=='1') {res="0"+res; check=true;}
        }
        if (check) res="1"+res;
        return Long.parseLong(res);
    }
    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out=new PrintWriter(System.out);
        int n=Integer.parseInt(in.readLine());
        long count=0;
        long i=1;
        while (i<=n)
        {
            count++;
            i=nextBit(i);
        }
        out.println(count);
        out.close();
    }

}
