using System;

public class Program

{

    public static void Main()

    {

        A a = new A();

        a.MethodM("a1 ", "a2 ");

        B b = new B();

        b.MethodM("b1 ", "b2 ");

        C c = new C();

        c.MethodM("c1 ", "c2 ");

    }

}

​

public class A

{

    public virtual void MethodM(string a1, string a2)

    {

        Console.WriteLine("Inside class A MethodM: " + a1 + a2);

    }

}

​

public class B : A

{

    public override void MethodM(string b1, string b2)

    {

        Console.WriteLine("Inside class B MethodM: " + b1 + b2);

    }

}

​

public class C : A

{

    public override void MethodM(string c1, string c2)

    {

        Console.WriteLine("Inside class C MethodM: " + c1 + c2);

    }

}