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: physical activity 
Words: summer, roll, plummet, fall, exercise
Example Output: summer

Example Input: Category: elements 
Words: pay, cool, combustion, air, fire
Example Output: pay

Example Input: Category: weather 
Words: balanced, fair, endure, luke, warm
Example Output:
balanced