You already got an answer but if you actually wanted a reasonable answer that you are sure is correct you can just directly email Osu! even though they might not reply. Well I guess that's the purpose of the forums. Haha. Also don't get too ahead of yourself. I'm not sure of your skill (mine is terrible) but if you are a novice or intermediate player its not going to be a good idea to enter the world cup. Those people are insanely good. Well good luck practicing for the world cup!