Given a set of five words, generate the word from the set that does not belong (i.e. is the least relevant) with the other words. Words are separated by commas.

Example Input: confident, popular, classy, cool, chill
Example Output: chill

Example Input: fax, file, format, image, document
Example Output: fax

Example Input: bird, bus, fly, beetle, pounce
Example Output:
bus