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

Example Input: Category: chocolate food 
Words: cake, fudge, rich, invent, cream
Example Output: invent

Example Input: Category: food 
Words: frank, entree, goodies, concise, wiener
Example Output: concise

Example Input: Category: window material 
Words: glass, wood, coating, knifer, woodwork
Example Output:
knifer