using System;

// Extend the following visitor pattern with an additional city class 
// without touching existing code except additional lines in main.  The 
// "tourist" and "college" visitors must also be extended to visit your city.

interface city  // visitee interface
{
   void accept(visitor v);
}

interface visitor  // visitor interface
{
   void visit(NY n);
   void visit(LA n);
}

class NY : city
{
  public void accept(visitor v) { v.visit(this); }
}

class LA : city
{
  public void accept(visitor v) { v.visit(this); }
}

//// sample visitors
class tourist : visitor
{
   public void visit(NY n)
   {
       Console.WriteLine("goto statue of liberty");
   }
   public void visit(LA n)
   {
       Console.WriteLine("goto hollywood");
   }
}//tourist

class collegevisitor : visitor
{
   public void visit(NY n)
   {  Console.WriteLine("goto NYU");  }
   public void visit(LA n)
   {  Console.WriteLine("goto UCLA"); }
}//collegevisitor

public class vex
{
  public static void Main()
  {
     city[] Cs = {new NY(), new LA()};
     visitor v = new tourist();
     foreach(city c in Cs) c.accept(v);
  }//Main
}