Hello tj.jeong2, Thank you so much for listening to the entire lecture. Thank you for your hard work! Have you checked out the book along with the lecture? The lecture includes content that is not in the book or the latter part of the content that is not covered in the book, so there are many differentiated parts when compared to the book. If you listened to the lecture after reading the entire book, it may have felt like a review, but for those who did not, we prepared it in a format that can definitely be of great help. Also, since the lecture introduction clearly states that it is based on the book, it feels a little disappointing that you gave a 1-point review because it is similar to the book. We will refer to your valuable opinions to provide better lectures in the future. Once again, thank you for your interest in the lecture, and we will continue to provide good content in the future.