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.

Ex Input:
forward, opposite of up, unhappy, downward, down

Ex Output:
unhappy


Ex Input:
neck, swift, egret, tackle, crane

Ex Output:
tackle


Ex Input:
prison, pretty, fine, prime, wispy

Ex Output:

pretty