/**
*  Anything that has a volume level is audible.
*/
public interface Audible
{
    public int getVolume();
}

/**
* Anything that has a recharge method is rechargeable
*/  
public interface Rechargeable
{
    public void recharge();
}

/**
 * Class representing a generic loud toy. 
 * Exists only to serve as a superclass.
 */
public abstract class LoudToy
{
    private int volume;

    public LoudToy(int volume)
    {
        this.volume = volume;
    }

    public abstract void makeNoise();

    public int getVolume()
    {
        return volume;
    }

}


/**
 * A rechargable toy robot.
 */
public class ToyRobot extends LoudToy
{
    private int chargeLevel;

    public ToyRobot()
    {
        super(10);
        chargeLevel = 5;
    }

    public void makeNoise()
    {
        System.out.println("Beep Beep!");
    }

    public void recharge()
    {
        chargeLevel = 10;
        System.out.println("Charged up!");
    }

}
/**
 * A toy sheep that says "Baaa."
 */
public class ToySheep extends LoudToy
{

    public ToySheep()
    {
        super(3);
    }

    public void makeNoise()
    {
        System.out.println("Baaa.");
    }

}

/**
* Cell phones, are not toys, but they have some
* functionality in common with some toys: 
* They are audible and rechargeable. 
*/
public class CellPhone implements Rechargeable, Audible
{
    private int volume;
    private int chargeLevel;
    
    public int getVolume()
    { 
        return 0;
    }

    public int makeCall()
    {
        System.out.println("Riing... Hello.");
    }
    
    public void recharge()
    {
        chargeLevel = 10;
        System.out.println("Phone is charged.");
      
    }

}