static void Main(string[] args)
        {
            //accessing private values...........
            Program one = new Program();

            Console.WriteLine(one.name);
            Console.WriteLine(one.num);
            //accessing public values............
            Programone o = new Programone();

            Console.WriteLine(o.model);
            o.display();
            o.display(5, 10);
            //static method......................
            int m = Programone.test(20, 14);

            Console.WriteLine($"the value of m is {m}");
            //making multiple objects and assigning values to it....
            one.gender  = "female";
            one.rollno  = 1217271;
            one.college = "jmit";
            Console.WriteLine($"{one.gender} ,{one.rollno},{one.college}");
            Program two = new Program();

            two.gender  = "male";
            two.rollno  = 1217281;
            two.college = "jmieti";
            Console.WriteLine($"{two.gender} ,{two.rollno},{two.college}");
            //parameterised constructor.............................
            Virtual v1 = new Virtual("heaven");

            Console.WriteLine(v1.name1);
            Virtual v2 = new Virtual("maruti", "black", 2000);

            Console.WriteLine(v2.model + " " + v2.color + " " + v2.year);
            //default constructor..................................
            Virtual v3 = new Virtual();
            //copy constructor
            Virtual v4 = new Virtual("this is copy constructor", 300);
            Virtual v5 = new Virtual(v4);

            //abstract classes......................................
            template obj;

            obj = new sampleOne();
            obj.templateOne();
            obj = new sampleTwo();
            obj.templateOne();
            obj.nonAbstract();
            //..........................................................
            //interfaces implementation.................................
            Myclass ob1 = new Myclass();

            ob1.show();
            int val = ob1.sum(20, 10);

            Console.WriteLine(val);
            //getter and setter method..................................
            Student s = new Student();

            s.Name = "Parneet Kaur Vig";
            Console.WriteLine("Name is:" + s.Name);
            Console.ReadLine();
            Console.ReadKey();
        }
 //copy constructor
 public Virtual(Virtual v4)
 {
     topic_name = v4.topic_name;
     article_no = v4.article_no;
     Console.WriteLine($"the topic name is- {topic_name} and the article number is {article_no}");
 }