Untitled

 internal class Program
 {
      public class Shape
     {
        public void draw()
         {
             Console.WriteLine("Draw Shape");
         }
        public void erase()
         {
             Console.WriteLine("Erase Shape");
         }
     }
      public class Circle : Shape
     {
         public void draw()
         {
             Console.WriteLine("Draw Circle");
         }
          public void erase()
         {
             Console.WriteLine("Erase Circle");
         }
     }
     public class Triangle : Shape
     {
         void draw()
         {
             Console.WriteLine("Draw Triangle");
         }
         public void erase()
         {
             Console.WriteLine("Erase Triangle");
         }
     }
     public class Square : Shape
     {
         public void draw()
         {
             Console.WriteLine("Draw Square");
         }
         public void erase()
         {
             Console.WriteLine("Erase Square");
         }
     }
     static void Main(string[] args)
     {
         Shape shape = new Shape();
         shape.draw();
         shape.erase();
         Circle circle = new Circle();
         circle.draw();
         circle.erase();
         Triangle triangle = new Triangle(); 
         triangle.draw();
         triangle.erase();
         Square square = new Square();
         square.draw();
         square.erase();
     }
 }