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: excavator, steam roller, concrete pourer, swallow, crane
Example Output: swallow

Example Input: Category: police punishment 
Words: ticket, comfortable, prime, custody, fine
Example Output: comfortable

Example Input: Category: mode of transportation 
Words: car, wave, drive, ant, fly
Example Output:
ant