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:
recruit, replace, sack, heat, fire

Ex Output:
heat

Ex Input:
foot, knee, eye, leg, ounce

Ex Output:
ounce

Ex Input:
area, fat, protein, thin, angular momentum

Ex Output:
protein