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.

I liked this book a lot. It was cool how there was a book within the book, but at first it was confusing because the format wasn't clear. But it was a fun mystery!
4