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: construction 
Words: dump truck, swift, crane, upraise, windlass
Example Output: swift

Example Input: Category: social gathering 
Words: club, group, meeting, grilled cheese, convention
Example Output: grilled cheese

Example Input: Category: animal 
Words: bird, bats, train, fly, eagle
Example Output:
train