You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[6a-cyano-5-hydroxy-4-(3-hydroxy-4-methyloct-1-enyl)-3a,4,5,6-tetrahydro-3H-cyclopenta[b]pyrrol-2-yl]butanethioic S-acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H32N2O3S
assistant