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: geographical property 
Words: mountain, flat, hill, mansion, plain
Example Output: mansion

Example Input: Category: body part 
Words: heel, shin, pound, finger, foot
Example Output: pound

Example Input: Category: police punishment 
Words: fine, prime, firstrate, comfortable, ticket
Example Output:
comfortable