Given a set of five words, generate the word from the set that does not belong (i.e. is the least relevant) with the other words. Words are separated by commas.

Example Input: parrot, goose, crane, swallow, excavator
Example Output: excavator

Example Input: ring, deck, pack, box, level
Example Output: pack

Example Input: fearful, content, thing, tools, substance
Example Output:
fearful