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;
import java.util.*;
import java.util.HashMap;
import java.util.stream.StreamSupport;

/**
 * Created by harish.sharma on 10/9/16.
 */
public class A1 {

    public static List<Integer> listBinary = new ArrayList<>();

    static {
        char[] ar = {'0', '0', '0', '0', '0', '0', '0', '0', '0' , '0'};
        List<char[]> chars = new ArrayList<>();
        chars.add(ar);
        for (int i = 0; i < 10; i++) {
            List<char[]> back = new ArrayList<>();
            for (int j = 0; j < chars.size(); j++) {
                char[] characters = Arrays.copyOf(chars.get(j), 10);
                characters[i] = '1';
                back.add(chars.get(j));
                back.add(characters);
            }
            List<char[]> temp;
            temp = back;
            back = chars;
            chars = temp;
        }
        for (char[] a : chars) {
            listBinary.add(Integer.parseInt(new String(a)));
        }
        Collections.sort(listBinary);
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        Integer in = Integer.parseInt(br.readLine());
        int count = 0;
        for (int i = 1; i < listBinary.size(); i++) {
            if(listBinary.get(i)>in)
                break;
            else count++;
        }
        System.out.println(count);
        br.close();
    }
}
