Definition: You are given a review of Amazon's food products. Your task is to divide them into two classes: negative or positive, depending on the content of the review.
Input: This used to be a great food, but they've changed the formula and my dogs have suffered. Their customer service is very rude. My dogs showed signs of distress within the first 24 hours of eating the new formula. Explosive Diaherra, Vomiting, Fur became dull. Change it back Canidae!!!
Output:
Negative