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: poker 
Words: board, joker, deck, fold, apron
Example Output: apron

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

Example Input: Category: guitar part 
Words: amp, emotional, board, fret, string
Example Output:
emotional