Solution Review: Union and Intersection of Linked Lists

using System;
namespace chapter_3
{
    class Challenge_9
    {
        static void Main(string[] args)
        {
            LinkedList list1 = new LinkedList();  // creating lists
            LinkedList list = new LinkedList();
            var rand = new Random();
            int rand_num = rand.Next(5);
            Console.WriteLine("List 1 ");
            for (int i = 1; i < 5; i++)
            {
                rand_num = rand.Next(5);
                list.InsertAtHead(rand_num);    // inserting value in the list
            }
            list.PrintList();
            Console.WriteLine("List 2 ");
            for (int i = 4; i < 8; i++)
            {
                rand_num = rand.Next(5);
                list1.InsertAtHead(rand_num);    // inserting value in the list   
            }
            list1.PrintList();
            string check = list.Union(list, list1);  // calling union function
            Console.WriteLine("Union List : " + check);
            return;
        }
    }
}