You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4S,7S)-4-(3,4-dichlorophenyl)-7-(4-fluorophenyl)-1,3,4,6,7,8-hexahydroquinoline-2,5-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H16Cl2FNO2
assistant