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: moral characteristic 
Words: mild, equitable, unprejudiced, trustworthy, fair
Example Output: mild

Example Input: Category: physical property 
Words: fat, vitamin c, area, brittleness, absorption
Example Output: vitamin c

Example Input: Category: bird 
Words: crane, davit, swift, duck, swallow
Example Output:
davit