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: bird 
Words: ostrich, digger, sandpiper, crane, goose

Output: digger


Input: Consider Input: Category: corporate 
Words: solid, sustainability, streamline, firm, private

Output: solid


Input: Consider Input: Category: elements 
Words: ice, combustion, pay, cool, fire


Output: pay