I want to start a wiki on public server

I want to start a private wiki on a PUBLIC server, but I want the server to use Wikipedia-like wikis

By that I mean: same page looks, same coding, same everything

Does it exist? I can't download MediaWiki to my pc (and besides, I don't want to support my own wiki), and I don't want to use public server wikis that don't look and function like Wikipedia's do. And I don't want to use alternatives to wikis, like tiddly wiki or whatever.