You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(10S,11S,12S,15R)-6-hydroxy-7,15-dimethyl-13-oxapentacyclo[10.2.2.18,11.01,10.04,9]heptadeca-4,6,8-trien-14-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H20O3
assistant