using System;

public class Base {

}

​

public class Derived : Base {

}

​

​

​

public class Program

{

    public static void Main() {

        Base b = new Base();

​

        var ans1 = b switch {

            Derived der => "Derived!",

            Base bas => "Base!",    

        };

​

        Console.WriteLine(ans1);

    }

}