note Anonymous Monk <p><i> could you tell me why? How would I recognize that I needed recursion there?</i> <p> If you have a set, that you need to <b>divide</b>, you you probably need recursion <p> See [href://https://en.wikipedia.org/wiki/Recursion_%28computer_science%29|Recursion (computer science)] and [href://https://en.wikipedia.org/wiki/Divide_and_conquer_algorithm|Divide and conquer algorithm] 1003519 1003609 12