You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-(4-chlorophenyl)-8,8-dimethyl-2-methylsulfanyl-5,5a,7,9,9a,10-hexahydro-3H-pyrimido[4,5-b]quinoline-4,6-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H22ClN3O2S
assistant