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 [(8R,9S,13S,14S,17R)-17-ethynyl-17-hydroxy-13-methyl-6-oxo-7,8,9,11,12,14,15,16-octahydrocyclopenta[a]phenanthren-3-yl] acetate .
user
C22H24O4
assistant