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: weather 
Words: cold, luke, fair, mild, light
Example Output: light

Example Input: Category: employment activity 
Words: promote, ice, retire, ban, fire
Example Output: ice

Example Input: Category: animal 
Words: fish, shark, dog, dolphin, trap
Example Output:
trap