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.

Ex Input:
Category: social gathering
Words: group, clan, team, club, doorstep

Ex Output:
doorstep

Ex Input:
Category: secretary duty
Words: answer calls, image, organize, file, correspondence

Ex Output:
image

Ex Input:
Category: mode of transportation
Words: bus, fly, flutter, swim, ant

Ex Output:
ant