Given reviews from Amazon, classify those review based on their content into two classes: Negative or Positive.

Example Input: If you are not in really good shape this is a great product to get ready for P90X. It does get kind of boring because you are doing the same workouts every other day, but they do work. It is only about 30 mins but it is amazing how well it works.
Example Output: Positive

Example Input: If you're willing to trade a little style for some substance and save some money in the bargain, this is a very recommendable device. My Apple PowerBook power supply died in what is apparently typical fashion - sparking, crumbling wire where it meets the brick - and none of the Apple stores or CompUSAs in Atlanta had any in stock (which is curious in itself). I resorted to Amazon and decided to try this one out and I've been pretty happy with it. It seems sturdily constructed, and the breakaway cable is a surprisingly handy way to save on tangles. I do miss the plug-in charging light, but that's about it.
Example Output: Positive

Example Input: A few years ago I bought a second hand copy of this book. During this time I must have read it at least once a year. I like it that much.It is a book about what humanity could aspire to become if we can put away the mistakes of the past and present.The arguments I've read that this is a unrealistic fantasy.... this is a book of fiction that portraits the thought and maybe the wishes of the author. You can agree with them or not.This is one of the few books that I would recommend to a beginning SF reader. It is not too difficult and a pleasure to read, and unlike many other books you are not left with a feeling of light depression because every main character died or had some other terrible fate happen to them.If you are interested in other works of Mr. Hogan I would recommend 'The Giant Novels' and 'The Genesis Machine'.
Example Output:
Positive