using System.Collections;
public static void Main()
Console.WriteLine("{0} {1} {2}", a1.GetHashCode(), a2.GetHashCode(), a3.GetHashCode());
Hashtable htb = new Hashtable();
Console.WriteLine(htb.Contains(a1).ToString());
Console.WriteLine(htb.Contains(a2).ToString());
Console.WriteLine(htb.Contains(a3).ToString());