using System;

public class Program:Airtel4G

{

    public static void Main()

    {   

        ImplementInterface.Add();

        ImplementInterface obj = new ImplementInterface();

        obj.Sub();

        obj.Minus();

        Program objp = new Program();

        objp.Myplan();

    }   

}

​

public class ImplementInterface:Intex, IComputer, IBattery

{

    public void Display()

    {   

        Console.WriteLine("Hello World");

    }   

    public override void Sub()

    {

        Console.WriteLine("Substract");

    }

}

​

public interface IComputer

{

    void Display();

}

​

interface IBattery

{

    void Display();

}

​

public abstract class Intex

{

    public static void Add()

    {

        Console.WriteLine("I'm Abstract Class");

    }

    public abstract void Sub(); 

    public void Minus()

    {

        Console.WriteLine("I'm Minus method");

    }

}

​

public class Airtel4G

{

    public virtual void Myplan()

    {

        Console.WriteLine("I'm Virtual method");

    }

}