You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(6S,8R,9S,10R,13S,14S)-4-hydroxy-6,10,13-trimethyl-2,6,7,8,9,11,12,14,15,16-decahydro-1H-cyclopenta[a]phenanthrene-3,17-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H28O3
assistant