import java.io.*;

public class DecimalToBinaryMain
{
	public static void main (String[ ] args)
	{
		new DecimalToBinaryMain().readAndProcessInputs();
	} // method main

	/**
	 * Reads in non-negative integers (until sentinel of "-1" reached) and 
 	 * prints out their binary equivalent.
 	 * 
	 */
	public void readAndProcessInputs() 
	{
        	final String SENTINEL = "-1";

        	final String SENTINEL_MESSAGE = "\nThe sentinel is " + SENTINEL + ".\n";

        	final String PROMPT =
	            	"\nIn the Input line, please enter a non-negative base-10 integer: ";

        	final String RESULT_MESSAGE = "The binary equivalent is ";

        	BufferedReader reader = new BufferedReader 
					(new InputStreamReader (System.in));

        	String line;

        	System.out.println (SENTINEL_MESSAGE);
        	while (true)
        	{
	 		try
        	    	{
            			System.out.print (PROMPT);
            			line = reader.readLine();
            			if (line.equals (SENTINEL))
                			break;            
                        	System.out.println (RESULT_MESSAGE +
				getBinary (Integer.parseInt (line)));
             		} // try
	 		catch (IOException e)
	 		{
				System.out.println (e);
	 		} // catch IOException
            		catch (IllegalArgumentException e)
            		{
                		System.out.println (e);
            		} // catch IllegalArgumentException
        	} // while
    	} // method readAndProcessInputs

	
	/**
	 *
	 * Determines the binary equivalent of a non-negative integer.  The worstTime(n)
	 * is O(log n), where n is the given integer.
	 *
	 * @param n the non-negative integer, in decimal notation.
	 *
	 * @return a String representation of the binary equivalent of n.
	 *	 
	 * @throws  IllegalArgumentException if n is negative.
	 */
	public static String getBinary (int n) 
	{
 		if (n < 0)
         	     	throw new IllegalArgumentException();
       		if (n <= 1)
          		return Integer.toString (n);
       		return getBinary (n / 2) + Integer.toString (n % 2);
 	} // method getBinary

} // class DecimalToBinaryMain