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.

Ex Input:
duck, get down, fall, stoop, cow

Ex Output:
cow


Ex Input:
fine, prime, firstrate, custody, ok

Ex Output:
ok


Ex Input:
ram, document, format, file, fax

Ex Output:

fax