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: mode of transportation 
Words: spider, fly, drive, train, soar
Example Output: spider

Example Input: Category: physical activity 
Words: dog, push, duck, squat, jog
Example Output: dog

Example Input: Category: animal 
Words: fly, grasshopper, jump, waggle, wave
Example Output:
wave