A melodrama that uniquely dances within several genres (slice-of-life, corruption, school bullying, romance) while connecting its very essence with mathematics. Huge fan of both leads. Watched Lee Do Hyun last in Youth of May (one of my all-time favorite kdramas) and was not disappointed by his role here. OST was beautiful and well-placed.

Well worth the watch. Some commentators here had a lot of prejudice toward the misconception that there would be a pedophilic or predatory student-teacher relationship, but it's nothing like that whatsoever. I've also seen many reviewers leave poor ratings because of their personal distaste for math. I also hate math, but I really appreciated the unique way it was implemented for this drama. All around solid cast with several worthy antagonists.