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: body part 
Words: inch, head, foot, ear, finger
Example Output: inch

Example Input: Category: emotional status 
Words: concerned, board, nervous, emotional, fret
Example Output: board

Example Input: Category: construction 
Words: windlass, excavator, crane, hummingbird, steam roller
Example Output:
hummingbird