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: secretary duty 
Words: answer calls, image, organize, file, correspondence
Example Output: image

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

Example Input: Category: military rank 
Words: fighter, colonel, general, boring, private
Example Output:
boring