You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (8S,9S,10R,13R,14S,17S)-17-ethyl-10,13-dimethyl-1,2,3,6,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthrene-7,7-diol .
user
C21H34O2
assistant