Given the task definition, example input & output, solve the new input case.
Given reviews from Amazon, classify those review based on their content into two classes: Negative or Positive.
Example: I've read this book with much expectation, it was very boring all through out the book
Output: Negative
Review writer does not like the book because it was boring, therefore it is a negative review.

New input case for you: I wanted a reliable second battery for my camera to take on an extended overseas vacation. I was concerned about "OEM" off-brands (which may be OK, but some reviewers advised caution). I was not disappointed by buying the Canon brand named battery which appears to function exactly as my original battery. The Amazon price was much better than I could find locally, and the delivery time was just a few short days after ordering.
Output:
Positive