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: elements 
Words: pay, cool, combustion, air, fire

Ex Output:
pay


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

Ex Output:
doorstep


Ex Input:
Category: corporate 
Words: alignment, inflexible, leverage, sustainability, firm

Ex Output:

inflexible