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.

Input: Consider Input: Category: elements 
Words: fire, retire, ice, air, earth

Output: retire


Input: Consider Input: Category: nutritional value 
Words: heavy, fat, protein, obese, carbs

Output: obese


Input: Consider Input: Category: animal 
Words: fly, bats, eagle, walk, bird


Output: walk