please pardon my ignorance, but to me a tower of hanoi question as a middle-schooler was the hardest thing to comprehend. but after learning about it, it is no longer quite as challenging to tackle.
i understand that there are very hard questions for the olympiad. but it might be possible to learn about some recurring types of them by looking at past instances. it may not be the meta for IMO but has been for other kinds of exams.