The Third Teaching Building,

After the second semester of his sophomore year, Lu Cheng met Xu Lei in a university physics experiment class, and went to study with him in a small classroom in the third teaching building, and then met Li Ping and Liu Lu. The four of them, from different majors, came together because of their studies and fell in love with each other over time. Lu Cheng and Xu Lei both like Li Ping, Li Ping dislikes them both, and Liu Lu likes Lu Cheng. After the first semester, Liu Lu left; after the second semester, Xu Lei left; at the end of the third semester, Lu Cheng left. Finally, Lu Cheng met Liu Lu at the postgraduate entrance examination site...