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

Example Input: Category: social gathering 
Words: place, club, outing, lettuce, group
Example Output: lettuce

Example Input: Category: measurement unit 
Words: centimeter, leg, mile, meter, foot
Example Output: leg

Example Input: Category: animal 
Words: dog, horse, hamster, fish, wrestle
Example Output:
wrestle