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: social gathering 
Words: club, bar, dance hall, discothek, roll
Example Output: roll

Example Input: Category: poker 
Words: level, blind, pack, draw, deck
Example Output: level

Example Input: Category: type of rigidity 
Words: firm, solid, unyielding, rigged, united
Example Output:
united