You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (4S)-7,12-dihydroxy-4,5,5,14-tetramethyl-3-oxatetracyclo[6.6.1.02,6.011,15]pentadeca-1(15),2(6),7,11,13-pentaene-9,10-dione .
user
C18H16O5
assistant