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: direction 
Words: up, descending, down, lower, melancholy
Example Output: melancholy

Example Input: Category: animal 
Words: swim, dive, fly, car, bee
Example Output: car

Example Input: Category: physical activity 
Words: drop, fall, leaves, bend, exercise
Example Output:
leaves