You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3R,4S)-5,7-dichloro-6-(1H-indol-7-yl)-2,2,4-trimethyl-3,4-dihydro-1H-quinolin-3-ol is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H20Cl2N2O
assistant