Hello, student. We apologize for the poor sound quality in the lecture. There was an issue during the initial lecture production, so we significantly reduced the course fee. We plan to improve and re-register it when conditions allow in the future. We ask for your understanding on this matter, and have a great day. For reference, if you would like to listen using English subtitles, please refer to the following link: https://www.youtube.com/playlist?list=PLRnDjo-4KCAq5BprqcbQb-cZvjY7MJpqb