You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (1S,2S,3S,5R,11R,12S,15S,16S)-15-hydroxy-2,16-dimethylpentacyclo[9.7.0.02,8.03,5.012,16]octadec-7-en-6-one into molecular formula.
user
C20H28O2
assistant