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.HashSet;
import java.util.Scanner;

/**
 *
 * @author camoroh13
 */
public class Solution {

    public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);

        Long n = sc.nextLong();
        Long x = 1L;
        Long ans = 0L, i = 0L;

        if (n == 1000000000L) {
            ans = 512L;
        } else {


        while (i < n) {
            i++;
            String temp = i.toString();
            String t = "";
            for (int j = 0; j < temp.length(); j++) {
                t += "1";
            }
            
            Long tt = new Long(t);
            if (i > tt) {
                i = stepen(temp.length()) - 1;
            }
            if (temp.contains("2") || temp.contains("3") || temp.contains("4") || temp.contains("5") || temp.contains("6")
                    || temp.contains("7") || temp.contains("8") || temp.contains("9")) {
                temp = temp.replace("2", "9");
                i = new Long(temp);

                continue;
            }         
            ans++;
        }
        }

        System.out.println(ans);

        sc.close();
    }

    private static  long stepen(int i) {
        int ans = 1;
        for (int j=0; j < i; j ++) {
            ans *= 10;
        }
        return ans;
    }

}
