public class Sky {
	private ArrayList<Cloud> clouds;
	public Sky() {
		clouds = new ArrayList<Cloud>(100);
	}

	 public boolean add (Cloud c) {
		clouds.add(c);
		return true;
	 }

	public float getMeanHeight() {
		float sum = 0;
		for (int i= 0; i < clouds.size(); i++) {
			sum = sum + clouds.get(i).getHeight();
		}
		return sum / clouds.size();
	}
	public static void main (String[]args)
	{
		StratusCloud strat = new StratusCloud(100, 1000);
		if (!strat.rain().startsWith("It is raining"))
			System.out.println("Bad StratusCloud::rain");
		CumulusCloud cumu = new CumulusCloud(200, 2000);
		if (!cumu.rain().startsWith("It is raining"))
			System.out.println("Bad CumulusCloud::rain");
		CirrusCloud cirr = new CirrusCloud(300, 3000);
		if (!cirr.rain().startsWith("I cannot make"))
			System.out.println("Bad CirrusCloud::rain");

		Sky sky = new Sky();
		sky.add(strat);
		sky.add(cumu);
		sky.add(cirr);
		float mean = sky.getMeanHeight();
		if (mean < 1799 || mean > 1801)
			System.out.println("Bad mean height: expected 1800, saw " + mean);
		System.out.println("Everything (else) is ok");
			}

		}