All right. Dr Yao Bowen is a doctoral student in Peking University Institute of Mathematical Sciences. He won the gold medal in the 52nd International Mathematical Olympiad (IMO) and has excellent professional knowledge. He has been teaching in the first-line training class of mathematics competition, and he is good at all subjects of mathematics competition with high quality. Mathematical competition is one of the effective means to discover mathematical talents. Mathematics competition in the modern sense began in Hungary. Most of the winners of some major mathematics competitions have made great achievements in their later careers.