You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(9R,11R)-9,11-bis(4-chlorophenyl)tetracyclo[10.5.0.02,7.08,13]heptadeca-2,4,6,12,14,16-hexaene-1,8-dicarbonitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C31H20Cl2N2
assistant