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.
//Problem: Hexadecimal's Numbers (https://codeforces.com/problemset/problem/9/C)
//Status: Not accepted

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

public class _0009C {
    private static InputReader infile = new InputReader();
    private static PrintWriter outfile = new PrintWriter(System.out);

    public static void main(String[] args) throws IOException {
        int n = infile.nextInt();
        Set<Integer> set = new HashSet<Integer>();
        recur(n, "", set);
        outfile.println(set.size());

        outfile.close();
    }

    private static void recur(int n, String num, Set<Integer> set) {
        if(num.length() == ("" + n).length()) {
            if(Integer.parseInt(num) <= n && Integer.parseInt(num) != 0)
                set.add(Integer.parseInt(num));
            return;
        }
        
        recur(n, num + '0', set);
        recur(n, num + '1', set);
    }

    static class InputReader {
        private static BufferedReader infile;
        private static StringTokenizer st;

        public InputReader() {
            infile = new BufferedReader(new InputStreamReader(System.in));
        }

        public String next() throws IOException {
            if(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(infile.readLine());
            return st.nextToken();
        }

        public String nextLine() throws IOException {
            return infile.readLine();
        }

        public int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        public long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }
    }
}