Get the height of a binary tree. O(n)

BSTGetHeight.cs

class Node
{
    public Node(int data) => Data = data;

    public int Data { get; }
    public Node Left { get; set; }
    public Node Rigth { get; set; }

    public void Add(int value)
    {
        if (value < Data)
        {
            if (Left is null)
                Left = new Node(value);
            else
                Left.Add(value);
        }
        else
        {
            if (Rigth is null)
                Rigth = new Node(value);
            else
                Rigth.Add(value);
        }
    }

    public int Height() => Math.Max(Left is null ? -1 : Left.Height(), 
                                        Rigth is null ? -1 : Rigth.Height())
                                        + 1;

class Program
{
    static void Main(string[] args)
    {
        var root = new Node(60);

        root.Add(50);
        root.Add(55);
        root.Add(40);
        root.Add(65);
        root.Add(63);
        root.Add(67);

        Console.WriteLine(root.Height()); //2
    }
}