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 (1R,4S,7R,10S)-12,13-dimethylidene-16-oxapentacyclo[8.4.3.14,7.01,10.03,8]octadeca-3(8),5-diene-15,17-dione .
user
C19H18O3
assistant