using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Kirill3
{
    class Program
    {
        static void Main()
        {
            LinkedList<int> list = new LinkedList<int>();
            list.AddFirst(1);
            list.AddFirst(2);
            list.AddLast(3);
            foreach (var item in list)
            {
                Console.WriteLine(item);
            }

            LinkedListMine l = new LinkedListMine();
            l.AddLast(1);
            l.AddLast(2);
            l.AddLast(3);
            l.AddFirst(4);
            l.AddLast(5);
            l.Print();


            //пример
        }


        class LinkedListMine
        {
            public Node First;
            public Node Last;

            public void AddFirst(int i)
            {
                if(First == null)
                {
                    First = new Node(i);
                    Last = First;
                    return;
                }

                var newFirst = new Node(i);
                First.Prev = newFirst;
                newFirst.Next = First;
                First = newFirst;
            }

            //добавить функцию ADD AFTER
            public void AddAfter(Node node, int value)
            {

            }

            //добавить функцию Find
            public Node Find(int value)
            {
                return null;
            }

            public void AddAfter(int valueAfter, int value)
            {
                AddAfter(Find(valueAfter), value);
            }



            //Улучшить с помощтю ссылки на Last
            public void AddLast(int i)
            {
                if(First == null)
                {
                    First = new Node(i);
                    Last = First;
                    return;
                }

                Node prev = First;
                Node current = First.Next;
                while(current != null)
                {
                    prev = current;
                    current = current.Next;
                }
                current = new Node(i);
                prev.Next = current;
                current.Prev = prev;

                Last = current;
            }

            public void Print()
            {
                Node current = First;
                Console.WriteLine();
                while (current != null)
                {
                    Console.Write(current.Value);
                    Console.Write(" ");
                    current = current.Next;
                }
                Console.WriteLine();
            }
        }

        class Node
        {
            public int Value;
            public Node Next;
            public Node Prev;

            public Node(int value)
            {
                Value = value;
            }
        }
    }
}