You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named (9S,10S)-9,10-dihydroxyspiro[9,10-dihydro-1H-pyrano[2,3-h]quinoline-8,1'-cycloheptane]-2-one is given. What is its corresponding molecular formula?
user
C18H21NO4
assistant