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.text.DecimalFormat;
import java.util.*;


public class Main {

    static class Task {
        //////////////////  Solution    /////////////////////////////////////
        boolean isBinary(int n){
            while(n > 0){
                if (n%10 != 1 && n%10 != 0) return false;
                n/=10;
            }
            return true;
        }
        public void solve(InputReader in, PrintWriter out) throws Exception {
            int n = in.nextInt();
            int f = numbers(n);

            long res = 0;
            res = (long)Math.pow(2,f-1)-1;
            int k = Integer.parseInt(Integer.toBinaryString((1 << f)-1));
            n = (k <= n) ? k : n;
            for (int i = (int)Math.pow(10, f-1); i <= n; i++){
                if (isBinary(i)) res++;
            }
            out.println(res);
        }
        int numbers(int n){
            int c = 0;
            while(n > 0){
                c++;
                n /= 10;
            }
            return c;
        }
        //////////////////////////////////////////////////////////////////////
    }

    public static void main(String[] args) throws Exception{
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task task = new Task();
        task.solve(in, out);
        out.close();
    }


    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }
        public long nextLong(){ return Long.parseLong(next()); }
        public int nextInt() {
            return Integer.parseInt(next());
        }
        public double nextDouble() { return Double.parseDouble(next()); }

    }
}
