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: construction 
Words: excavator, steam roller, concrete pourer, swallow, crane
Example Output: swallow

Example Input: Category: police punishment 
Words: prime, penalty, fine, mad, arrest
Example Output: mad

Example Input: Category: aesthetic characteristic 
Words: fair, well, even, alright, color
Example Output:
alright