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,9R,10S,13S,17R)-9-hydroxy-10,13-dimethylspiro[1,2,6,7,8,11,12,14,15,16-decahydrocyclopenta[a]phenanthrene-17,5'-oxolane]-2',3-dione .
user
C22H30O4
assistant