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: condominium, duplex, studio, flat, level
Example Output: level

Example Input: file, prepare, document, space, folder
Example Output: prepare

Example Input: solid, sustainability, firm, resistant, inflexible
Example Output:
sustainability