public class Program
{
public class A
//base class method, created with keyword 'virtual'
public virtual void Display()
System.Console.WriteLine("A::Display");
}
public class B :A
// dervied class methodm with new definition using override
public override void Display()
System.Console.WriteLine("B::Display");
public static void Main()
A a;
a = new A();
a.Display();
a = new B();
