You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(8R,9S,10R,13S,14S)-3,10,13-trimethyl-1,2,5,6,7,8,9,11,12,14,15,16-dodecahydrocyclopenta[a]phenanthren-17-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H30O
assistant