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: summer, roll, plummet, fall, exercise
Example Output: summer

Example Input: fax, file, format, image, document
Example Output: fax

Example Input: mansion, elevation, flat, duplex, even
Example Output:
elevation