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

[EX Q]: I just returned from a month-long trip to Vietnam and Cambodia, and I found this book extremely useful for Cambodia. Not so much for hotel listings, etc., but for no-nonsense background information on Angkor, Phnomh Penh, and Siem Reap. The Vietnam portion was helpful as well, but I relied more on the Lonely Planet and Rough Guide Vietnam editions for that country. I would definitely recommend this book to someone traveling to Cambodia over the Lonely Planet edition, which is *really* outdated.
[EX A]: Positive

[EX Q]: I bought this air mattress to use while my new bed was being shipped from back east, the bed lost air every night and I woke up almost on the floor. I tried to send it back but it was impossible to get back into the box.
[EX A]: Negative

[EX Q]: this book seemed to take awhile to get to me but it still came within the specified time frame so, all's well I guess, and the condition of the book was quite acceptable.
[EX A]:
Positive