import java.util.*;

class Broker implements Observer {
	public void update(Observable subject, Object msg) {
		// respond to rate change
	}
}

class Bank implements Observer {
	private Rate someRate;
	public Bank(Rate rate) {
		someRate = rate;
		someRate.addObserver(this);
	}
	public void update(Observable subject, Object msg) {
		// respond to rate change
	}
}

public class Rate extends Observable {
   private double rate;
   public void setRate(double newRate) {
	   rate = newRate;
	   setChanged();
	   notifyObservers();
   }
}