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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{

    public static void main(String[] args)throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String s = br.readLine();
        int d =0;
        int l = s.length();
        for (int i = 0; i < l; i++) {
            if (s.charAt(i) > 49){
                d+=(int) Math.pow(2, l-i)-1;
                break;
            }
            else if (s.charAt(i) == 49)
                d += Math.pow(2,l-i-1);
        }
        System.out.println(d);
    }
}
