Instructions: In this task, you're given a review from Amazon. 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, 4: good, 5: extremely good.
Input: I've used this to speed up the time required to bring water to a boil for beer brewing on a gas burner. It will heat 5 gallons of water on it's own, but not to boiling in my tests.
Output:
4