You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4aS,5R,8aR)-5-(5-bromo-2-hydroxyphenyl)-2,3,4a,8a-tetrachloro-6-ethenyl-5,8-dihydronaphthalene-1,4-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H11BrCl4O3
assistant