General question about filtering subreddits from /r/all

When I add a subreddit to be filtered out do I need to include /r/ or /r/ or just the subreddit title (for example mylittlepony)? Previously I filtered out r/fffffffuuuuuuuuuuuu/ by using r/fffffffuuuuuuuuuuuu/, but when I added starcraft and mylittlepony with the /r/ in front it didn't seem to work.