I enjoyed it! 1. Using "instanceof supertype supertype variable" to do type casting in Java 16, 2. Using static in the abstract store class in the second problem of 'Problems and Solutions' using polymorphism was impressive. On the other hand, when I took the 'Problems and Solutions' lecture, I liked that it was related to my refactoring experience when I participated in the 'Uteco Free Course'. 3. I also purchased "Kim Young-han's Practical Java - Intermediate Part 1"! I added "Kim Young-han's Practical Java - Intermediate Part 2" to my cart, but I missed the payment during the discount period, but the lecture was interesting, so I plan to purchase Intermediate Part 2 after watching Intermediate Part 1! I will continue learning with the next lecture. Thank you for making the lecture!