Given the task definition and input, reply with output. 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.

Great continued development of Charlie Moon and Scott Parris - great to encounter a mystery where there are really two lead characters - no sidekicks here. Excellent plot - hard to put down.
4