// $Id: hash.java,v 1.3 2001/03/02 02:17:29 doug Exp $
// http://www.bagley.org/~doug/shootout/

// this program is modified from:
//   http://cm.bell-labs.com/cm/cs/who/bwk/interps/pap.html
// Timing Trials, or, the Trials of Timing: Experiments with Scripting
// and User-Interface Languages</a> by Brian W. Kernighan and
// Christopher J. Van Wyk.

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

public class hash {

    public static void main(String args[]) throws IOException {
	int n = Integer.parseInt(args[0]);
	int i, c;
	String s = "";
	Integer ii;
	// the original program used:
	// Hashtable ht = new Hashtable();
	// John Olsson points out that Hashtable is for synchronized access
	// and we should use instead:
	HashMap ht = new HashMap();

	c = 0;
	for (i = 1; i <= n; i++)
	    ht.put(Integer.toString(i, 16), new Integer(i));
	for (i = 1; i <= n; i++)
	    // The original code converted to decimal string this way:
	    // if (ht.containsKey(i+""))
	    if (ht.containsKey(Integer.toString(i, 10)))
		c++;

	System.out.println(c);
    }
}