using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

} 

​

namespace Virtual_Method1

​

{

​

    class Circle

​

    {

​

        protected const double PI = 3.14;

​

        protected double Radious = 14.9;

​

        public virtual double Area()

​

        {

​

            return PI * Radious * Radious;

​

        }

​

    }

​

    class Cone : Circle

​

    {

​

        protected double Side = 10.2;

​

        public override double Area()

​

        {

​

            return PI * Radious * Radious;

​

        }

​

    }

​

    class Program

​

    {

​

        static void Main(string[] args)

​

        {

​

            Circle obj1 = new Circle();

​

            Console.WriteLine("Area is:-" + obj1.Area());

​

            Circle obj2 = new Cone();

​

            Console.WriteLine("Area is:-" + obj2.Area());

​

            Console.ReadLine();

​

​

        }

​

    }

​

}

​

namespace Virtual_Method_2

​

{

​

    class Student

​

    {

​

        string _studentName = "James";

​

        string _address = "California";

​

        public virtual void printdetails()

​

        {

​

            Console.WriteLine("Student Name:-" + _studentName);

​

            Console.WriteLine("Address:-" + _address);

​

        }

​

    }

​

    class Grade : Student

​

    {

​

        string _class = "Four";

​

        float _percent = 71.25F;

​

        public override void printdetails()

​

        {

​

            Console.WriteLine("Student Name:-" + _class);

​

            Console.WriteLine("Address:-" + _percent);

​

        }

​

    }

​

    class Program

​

    {

​

        static void Main(string[] args)

​

        {

​

            Student obj1 = new Student();

​

            Student obj2 = new Grade();

​

            obj1.printdetails();

​

            obj2.printdetails();

​

            Console.ReadLine();

​

        }

​

    }

​

}

​