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 love Mam bottles. Baby took them with no problems. The nipple doesnt collapse causing you to take them out of the babies mouth. I gave 4 stars because they dont heat up well with bottle warmers due to the thickness and base of bottle.
4