public class GcdCalculator
{
	public static int gcd (int p, int q)
	{
		int r;
		// p = Math.abs(p);
		// q = Math.abs(q);
		while (q != 0)
		{
			r = p % q;
			p = q;
			q = r;
		}
		return Math.abs(p);
	}

	protected static final String HINT = 
	   "Please call the gcd calculator with two integer arguments! ";

	public static void main (String[] args)
	{
		if (args.length < 2)
		{
			System.out.println("Missing Argument. " + HINT);
		}
		else
		{
			try 
			{
				System.out.println(gcd
				   (Integer.parseInt(args[0]), 
				    Integer.parseInt(args[1])));
			} 
			catch (Exception e) 
			{
				System.out.println
				   ("Wrong Argument. " + HINT + e.toString());
			}
		}
	}
}