You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[1-(2-ethoxyethyl)-2-imino-6-oxopiperidin-3-yl]-4-(methylamino)isoindole-1,3-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H22N4O4
assistant