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: measurement unit 
Words: meter, inch, foot, heel, pound
Example Output: heel

Example Input: Category: weather 
Words: 70, mild, fair, dishonest, clime
Example Output: dishonest

Example Input: Category: animal 
Words: walk, flap, fish, bird, fly
Example Output:
flap