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: animal 
Words: bus, leap, spider, run, fly
Example Output: bus

Example Input: Category: aesthetic characteristic 
Words: fine, custody, level, beautiful, attractive
Example Output: custody

Example Input: Category: bird 
Words: crane, sandpiper, davit, goose, ostrich
Example Output:
davit