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: aesthetic characteristic 
Words: pretty, probation, neat, fine, level
Example Output: probation

Example Input: Category: boxing terminology 
Words: deck, ring, head, knockout, glove
Example Output: head

Example Input: Category: guitar part 
Words: output cord, neck, sad, headstock, fret
Example Output:
sad