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.math.*;
import java.io.*;
public class ShortestPath {
//begin of the template--------------------------- 
    public static void main (String [] args) throws IOException {
        new ShortestPath().run();
    }
    StreamTokenizer in;
    PrintWriter out;
    int nextInt () throws IOException {
        in.nextToken();
        return (int)in.nval;
    }
    void run () throws IOException {
        in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        out = new PrintWriter(new OutputStreamWriter(System.out));
        solve();
        out.flush();
    }
    public static int ans = 0;
    public static int n;
    void rec (int x) {
        if(x > n) {
            return;
        }
        ans++;
        rec(10 * x);
        rec(10 * x + 1);
    }
    void solve () throws IOException {
        n = nextInt();
        rec(1);
        System.out.printf("%d", ans);
    }
//end of the template---------------------------
}
