In this task, you're given a review from Amazon's food products. Your task is to generate a rating for the product on a scale of 1-5 based on the review. The rating means 1: extremely poor, 2: poor, 3: neutral or mixed, 4: good, 5: extremely good. 

Example Input: For those who love salt and vinegar potato chips, this is the one to choose. The flavor is zippy and tart, with no unpleasant chemical aftertaste like the less "natural" versions of this snack. The 2-ounce bags are just right to share at lunch. The chips are a little greasy, and that's why I've given them 4 stars instead of 5.
Example Output: 4

Example Input: I bought 21 0z freeze dried liver. Half the container was filled with powder instead of pieces/chunks. I feel I was betrayed by the company. Hence I did not get what I paid for
Example Output: 3

Example Input: Fantastic tasting potato chips. I love the individual bags, great for kids and adults too. No trans fat, no cholesterol, no artifical stuff. Low in sodium and high in potassium, which is great for people like me with HBP. Only problem is Amazon is out of stock some times and price is high.
Example Output:
5