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

Example Input: This product requires a stereo player in which the balance is turned totally to the left. Most auto systems have that capability. However if you have Dolby or SurroundSound, it can be difficult (and maybe impossible) to play the cassette without hearing two recordings at the same time. Unfortunately neither the packaging nor the website will warn you of the problem. You therefore should think before buying. Once you have opened the packaging you may be unable to return the product.
Example Output: Negative

Example Input: Excellent product. I was having difficulty hearing and also getting a comfottable fit with the included ear hook that came with my Jabra JX-10 Series II Bluetooth headset. I removed the hook and attached one of the 6 gels that came in the pack to the headset and found that the volume increased 40% and I was able to achieve a comfortable fit. The headset is small enough and light enough that the gel holds the headset in the ear. I was about to give up on this headset (and all earhook type Bluetooth headsets) prior to getting the gels. If you are looking for a comfortable (and econimical) alternative for earhook type headsets, I strongly recommend that you give these a try. They are well worth the price.
Example Output: Positive

Example Input: i only used this bed about a dozen times. it was never really all that comfortable and the last time i inflated it, a huge lump developed right in the middle making it unusable. there is no way to get rid of the lump and it is rock hard solid. it raised up about 3 inches high and is about 15 inches in diameter. its too late to send it back now so its going in the dumpster. i have since read other reviews of intex doing the same thing. i will NEVER get another intex again...i am going back to aerobeds!
Example Output:
Negative