class MainProtocol {
	public final int isWaiting = 0;
	public final int sentData = 1;

	public int state = isWaiting;
	public String processInput(String dataIn) {
		String dataOut = null;
		switch (state) {
			case 0:
				if (dataIn == "Hello.") {
					dataOut = "Ello mate.";
					state = sentData;
				} else {
					dataOut = "Excuse me?";
				}
				break;

			case 1:

				break;
			default:

				break;
		}
		return dataOut;
	}
}