You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(3S,5S,9R)-2,8-dioxo-1,7-diazatricyclo[7.3.0.03,7]dodecan-5-yl]-3-methoxybenzamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H21N3O4
assistant