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: corporate 
Words: solid, sustainability, streamline, firm, private
Example Output: solid

Example Input: Category: police punishment 
Words: suspension, exquisite, prime, fine, flyaway
Example Output: exquisite

Example Input: Category: corporate 
Words: concerted, united, synergy, rough, firm
Example Output:
rough