You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule identified by S-[(1'R,2S,2'S,3'S,5'S,7'S,10'S,11'S,18'R)-7',11'-dimethyl-5,14'-dioxospiro[oxolane-2,6'-pentacyclo[8.8.0.02,7.03,5.011,16]octadeca-12,15-diene]-18'-yl] ethanethioate ?
user
C25H30O4S
assistant