You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(13S)-13-methyl-11-phenyl-2,6,7,8,11,12,14,15,16,17-decahydro-1H-cyclopenta[a]phenanthren-3-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C24H28O
assistant