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

Let me give you an example: I've read this book with much expectation, it was very boring all through out the book
The answer to this example can be: Negative
Here is why: Review writer does not like the book because it was boring, therefore it is a negative review.

OK. solve this:
i dont know why these guys are trying to cheat. i paid full amount and i was expected to receive a twin size airbed but when i opened it it is actual size is single sized matress! so this company is baad! will never suggest it to someone.
Answer:
Negative