You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance (8S,9S,10R,13R,14S)-16,16-difluoro-10,13-dimethyl-1,2,3,4,7,8,9,11,12,14,15,17-dodecahydrocyclopenta[a]phenanthrene .
user
C19H28F2
assistant