You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[1-[1-[(1S,2R)-2-methyl-1,2-dihydroacenaphthylen-1-yl]piperidin-4-yl]-2-oxo-3H-indol-3-yl]acetate is the IUPAC name of a molecule. Please give its molecular formula.
user
C28H27N2O3-
assistant