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: bird
Words: neck, tackle, derrick, crane, steam roller

Ex Output:
steam roller

Ex Input:
Category: mode of transportation
Words: swim, bike, soar, fly, jump

Ex Output:
jump

Ex Input:
Category: elements
Words: instruct, fire, flame, burn, air

Ex Output:
instruct