Is the C# compiler free?
<p>I'm joining the <a href="https://www.facebook.com/notes/facebook-hacker-cup/hacker-cup-2013-faq/" rel="nofollow">Facebook Hacker's Cup</a>. The rules say you can use any language with a free compiler; is C#'s free? I think so, but want to make sure...</p>

<p>I use Visual Studio Ultimate  (licensed from my school which is not free) and I would like to avoid having to learn a new language 1 week before the competition...</p>
