input question: Determine the topic of the question-answer pair. Question: "what is a constant in math??"; Answer: "A mathematical constant is a special number , usually a real number , that is "significantly interesting in some way"."? Topic:???
output answer: Mathematical constant

input question: Determine the topic of the question-answer pair. Question: "when does air bag deploy?"; Answer: "It is an occupant restraint system consisting of a flexible fabric envelope or cushion designed to inflate rapidly during an automobile collision ."? Topic:???
output answer: Airbag

input question: Determine the topic of the question-answer pair. Question: "how many presidents of the us?"; Answer: "There have been 43 people sworn into office, and 44 presidencies, as Grover Cleveland served two non-consecutive terms and is counted chronologically as both the 22nd and 24th president."? Topic:???
output answer: List of Presidents of the United States

input question: Determine the topic of the question-answer pair. Question: "what composer used sound mass?"; Answer: "A very early example is the opening of Jean-Fery Rebel 's ballet Les Elemens (173738), where chaos is represented by a gradually cumulating orchestral cluster of all seven notes of the D minor scale (Henck 2004, pp. 5254)."? Topic:???
output answer:
Sound mass