You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(8R,9S,10R,13S,14S,17R)-17-ethynyl-3-methoxy-10,13-dimethyl-16-methylidene-2,7,8,9,11,12,14,15-octahydro-1H-cyclopenta[a]phenanthren-17-ol is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H30O2
assistant