static void Main(string[] args) { var root = new CompositeNode(2); root.Add(new LeafNode(2)); root.Add(new LeafNode(10)); var composite = new CompositeNode(4); composite.Add(new LeafNode(2)); composite.Add(new LeafNode(6)); root.Add(composite); Console.WriteLine("Sum of all node values: ", root.Sum()); root.CheckEven(); }