I paid yesterday and finished it today. I bought it because I wanted to learn about more specific and high-level class design because I had watched other Java grammar lectures on YouTube or Inflearn, but it didn't seem to be like that. It was a little disappointing, but if other lectures teach a, b, c, this lecture teaches a, b, d, and I liked the content of d covered in this lecture. I came here after taking another grammar lecture, so I think it would be good for those who are not yet familiar with it to review.