Given a set of five words, generate the word from the set that does not belong (i.e. is the least relevant) with the other words. Words are separated by commas.

Example Input: fish, stingray, climbing, trap, hiking
Example Output: stingray

Example Input: current, history, wave, jetstream, whirlpool
Example Output: history

Example Input: blaze, combustion, sack, fire, heat
Example Output:
sack