static void Main()
{
Duck RubberDuck = new RubberDuck();
RubberDuck.PerformFly();
RubberDuck.PerformQuack();
RubberDuck.Display();
Duck FredTheEagle = new Eagle();
FredTheEagle.PerformFly();
FredTheEagle.PerformQuack();
FredTheEagle.Display();
Console.ReadKey();
}