using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        LinkedList ls = new LinkedList();

        ls.Push(4);

        ls.Push(3);

        ls.Push(5);

        ls.Push(1);

        ls.Push(2);

        ls.PrintList();

        Console.WriteLine();

        ls.InsertAfter(3,10);

        ls.PrintList();

        Console.WriteLine();

        ls.InsertAtEnd(99);

        ls.PrintList();

    }

}

​

public class Node

{

    public int Data;

    public Node Next;

    public Node(int d)

    {

        Data = d;

        Next = null;

    }

}

​

public class LinkedList

{

    public Node head;

    public LinkedList()

    {

        head = null;

    }

    public void PrintList()

    {

        var temp = head;

        while(temp != null)

        {

            Console.Write(" ==> ");

            Console.Write(temp.Data);

            temp = temp.Next;

        }

    }

    public void Push(int d)

    {

        Node n = new Node(d);

        if(head == null)

            head = n;

        else

        {

            n.Next = head;

            head = n;

        }

    }

    public void InsertAfter(int n, int d)

    {

        if(head == null)

            head = new Node(d);

        else

        {

            var temp = head;

            while(temp != null && temp.Data != n)

            {

                temp = temp.Next;

            }

            if(temp == null)

                return;

            else

            {

            Node newNode = new Node(d);

            newNode.Next = temp.Next;

            temp.Next = newNode;

            }

        }

    }

    public void InsertAtEnd(int d)

    {

        if(head == null)

            head = new Node(d);

        else

        {

        var temp = head;

        while(temp.Next != null)

        {

            temp = temp.Next;

        }

        var newNode = new Node(d);

        temp.Next = newNode;

        }

    }

}