using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}

public class BTree<T> ( T cargo, BTree<T> left, BTree<T> right) { 

    public T Cargo {get; set;} = cargo;

    public BTree<T> Left {get; set;} = left;

    public BTree<T> Right {get; set;} = right;

}

​

public class TreeNode<T>(T data)

{

    public T Data { get; set; } = data;

    public TreeNode<T> Parent { get; set; }

    public ICollection<TreeNode<T>> Children { get; set; } = new LinkedList<TreeNode<T>>();

​

    public TreeNode<T> AddChild(T child)

    {

        TreeNode<T> childNode = new TreeNode<T>(child) { Parent = this };

        this.Children.Add(childNode);

        return childNode;

    }

​

    // other features ...

}