I took the course last year, but it expired without me studying, so I bought it again this year. Thanks to this, I passed the exam. I also took several Udemy lectures, but the translation quality was not good, so it was difficult to understand, but Inflearn lectures were good because they only taught the key points. I think I got about 50% from solving problems. When I didn't understand well, I put the problem and answer in ChatGPT and asked for an easy explanation, and it helped me study. Instructor, please make more lectures. Thank you!