You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(1S,2R,3R,6S,9S,10R)-3,6,7,8,12,13,14,15-octachloropentacyclo[8.6.2.02,9.03,6.011,16]octadeca-7,11(16),12,14,17-pentaene-4,5-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H6Cl8O2
assistant