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: unyielding, concerted, firm, combined, united
Example Output: unyielding

Example Input: glass, acrylic, wood, metal, plate
Example Output: plate

Example Input: icy, optimist, warm, freezing, cool
Example Output:
optimist