using System.IO;
using System;

class Program
{
    public class Base
{
    public virtual string WhoAmI()
    {
        return "Base";
    }
}

public class NotVeryDerived
{
    public NotVeryDerived()
    {
        _base = new Base();
    }
    Base _base;

    public string WhoAmI(int a)
    {
        var baseResult  = _base.WhoAmI();
        return string.Format("{0} {1} {2}", baseResult, "Derived", a);
    }
}

    static void Main()
    {
        var a = new NotVeryDerived();
       Console.Write(a.WhoAmI(1));
    }
}