@ZozoFouchtra thank you for the suggestion. Yes, it makes sense. I will add more explanation to make it clear that each row of the first table will need to be compared to each row of the second table and will add more test cases.

@LiamSorta thanks. Your additional description will make the task clearer to beginners like myself.

Shouldn't the description state that the numbers are always integers? Also, if the numbers contain same values (e.g. [1, 1, 2, 4]), should the output have the duplicates as well (e.g. [1, 1, 2, 3, 4])? My current solution would fail in that case.