You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(1R,4S,8S,9S,17S)-14-methoxy-4,17-dimethyl-5-oxo-18-oxapentacyclo[12.3.1.01,9.04,8.012,17]octadecan-2-yl] thiocyanate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H29NO3S
assistant