Implementation Of Linked Lists Using Collections Name Space In C#

using System;
using System.Collections.Generic;
namespace LinkList {
    class Program {
        static LinkedList < int > ll = new LinkedList < int > ();
        static LinkedListNode < int > node;
        static void Main(string[] args) {
            Console.WriteLine(" LINKED LIST DEMO");
            int ch, x;
            Console.WriteLine("Linked List Operations");
            Console.WriteLine("1.AddFirst\n2.AddLast\n3.RemoveFirst\n4.RemoveLast\n5.Remove Specified\n6.Display\n7..Exit");
            while (true) {
                Console.Write("Enter your Choice : ");
                ch = Convert.ToInt16(Console.ReadLine());
                switch (ch) {
                    case 1:
                        Console.Write("Enter the Element to AddFirst : ");
                        x = Convert.ToInt16(Console.ReadLine());
                        ll.AddFirst(x);
                        display();
                        break;
                    case 2:
                        Console.WriteLine("Enter the Element to AddLast : ");
                        x = Convert.ToInt16(Console.ReadLine());
                        ll.AddLast(x);
                        display();
                        break;
                    case 3:
                        if (ll.Count == 0) {
                            Console.WriteLine("Nothing to Delete...!!!");
                            break;
                        } else {
                            Console.WriteLine("First Element Removed Successfully");
                            ll.RemoveFirst();
                            display();
                            break;
                        }
                    case 4:
                        if (ll.Count == 0) {
                            Console.WriteLine("Nothing to Delete...!!!");
                            break;
                        } else {
                            Console.WriteLine("Last Element Removed Successfully");
                            ll.RemoveLast();
                            display();
                            break;
                        }
                    case 5:
                        if (ll.Count == 0) {
                            Console.WriteLine("Nothing to Delete...!!!");
                            break;
                        } else {
                            Console.WriteLine("Enter the Element to Remove");
                            x = Convert.ToInt16(Console.ReadLine());
                            bool b = ll.Remove(x);
                            if (b == true) {
                                Console.WriteLine("Element Removed Successfully");
                                display();
                                break;
                            } else {
                                Console.WriteLine("Specified Node Does not Exist");
                                break;
                            }
                        }
                    case 6:
                        display();
                        break;
                    default:
                        Environment.Exit(0);
                        break;
                }
            }
        }
        public static void display() {
            if (ll.Count == 0) {
                Console.WriteLine("Nothing to Display...!!!");
            } else {
                Console.Write("Elements in the List are:");
                for (node = ll.First; node != null; node = node.Next) Console.Write(node.Value + " ");
                Console.WriteLine();
            }
        }
    }
}