static void Main(string[] args)
{
var tree = new Tree();
tree.Insert("romane");
tree.Insert("romanus");
tree.Insert("romulus");
tree.Insert("rubens");
tree.Insert("ruber");
tree.Insert("rubicon");
tree.Insert("rubicundus");
Console.WriteLine("predecessor of the word \"romanes\":" + tree.FindPredecessor("romanes"));
Console.WriteLine("successor of the word \"rom\":" + tree.FindSuccessor("rom"));
Console.WriteLine(tree.Lookup("romulus") ? "there" : "not there");
tree.Delete("romanus");
}