Read the description (again) and then come back. Now just give any integer between 1 and 20 inclusive. Note that this is the only question where the full set of correct answers is knowable in advance. On questions 2-12 the correct answer(s) will turn out to be some subset of this question's correct answers.
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20