using System;

using System.Collections.Generic;

​

public class Program

{

    public class Tree<T>

    {

        private TreeNode<T> root;

        public Tree(T val)

        {

            if (val == null)

            {

                throw new ArgumentNullException("Cannot insert value here");

            }

            root = new TreeNode<T>(val);

        }

        public Tree(T val, params Tree<T>[] children):

        this(val)

        {

            foreach (Tree<T> child in children)

            {

                root.AddChild(child.root);

            }

        }

        public TreeNode<T> Root

        {

            get{ return root;}

        }

    }

    public class TreeNode<T>

    {

        private T m_val;

        private List<TreeNode<T>> children;

        public TreeNode(T par1)

        {

            m_val = par1;

            children = new List<TreeNode<T>>();

        }

        public void AddChild(TreeNode<T> node)

        {

            children.Add(node); 

        }

        public TreeNode<T> GetChild (int idx)

        {

            return children[idx];   

        }

    }

    public static void Main()

    {

        Tree<int> tree = new Tree<int>(7, 

                                       new Tree<int>(19, 

                     new Tree<int>(1), new Tree<int>(12), new Tree<int>(31)),

                                       new Tree<int>(21),

                                       new Tree<int>(14, 

                            new Tree<int>(23), new Tree<int>(6))

                                       );

        Console.WriteLine("Hello World");

    }

}