using System;

public class Program

{

    public class ListNode {

     public int val;

     public ListNode next;

     public ListNode(int x) { val = x; }

     }

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Program p=new Program();

        ListNode nodenew = new ListNode(1);

        ListNode nodenew1 = new ListNode(3);

        nodenew.next=nodenew1;

        ListNode nodenew2 = new ListNode(4);

        nodenew1.next=nodenew2;

        ListNode node = new ListNode(2);

        ListNode node1 = new ListNode(3);

        node.next=node1;

        ListNode node2 = new ListNode(4);

        node1.next=node2;

        ListNode current = p.DeletefromFirst(nodenew);

        while(current!=null)

        {

        Console.WriteLine("This is merged:{0}",current.val);

            current=current.next;

        }

        ListNode current2 = p.DeletefromFirst(nodenew);

        while(current!=null)

        {

        Console.WriteLine("This is merged:{0}",current.val);

            current=current.next;

        }

        ListNode current1 = p.DeleteFromEnd(nodenew);

        while(current1!=null)

        {

        Console.WriteLine("This is merged:{0}",current1.val);

            current1=current1.next;

        }

    }

    public ListNode DeletefromFirst(ListNode head)

    {

        //ListNode current =head ;

        //current.next=head.next;

        head=head.next;

        return head;

    }

    public ListNode DeleteFromEnd(ListNode head)

    {

        ListNode current =head;

        while(current.next.next!=null)

        {

            current=current.next;

        }

        current.next=null;

        Console.WriteLine("This is Current value:{0}",current.val);

        return head;

    }

    public ListNode DeleteGivenVal(ListNode head,int val)

    {

        ListNode current =head;

        while(current.next.val!=val)

        {

            current=current.next;

        }

        current.next=current.next.next; 

        current.val=current.next.val;

        Console.WriteLine("This is deleted value:{0}",current.val);

        return head;

    }

}