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.util.*;
import java.lang.*;
import java.io.*;

public class Main {
    
    static long n, d;
    
    static long f(int i, String s) {
        if (i == d) {
            if (Long.parseLong(s) <= n) {
                return 1;
            } else {
                return 0;
            }
        }
        return f(i + 1, s + "0") + f(i + 1, s + "1");
    }
    
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line;
        String[] ar;
        StringBuilder sb = new StringBuilder();
        //-----------------------------------------------------------------------
        line = br.readLine();
        n = Long.parseLong(line);
        d = line.length();
        long ans = 1;
        for (int i = 2; i < d; i++) {
            ans += Math.pow(2, i - 1);
        }
        if (d > 1)
            ans += f(1, "1");
        sb.append(ans + "\n");
        //-----------------------------------------------------------------------
        System.out.print(sb);
    }
}