You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(Z)-2-(2,1,3-benzothiadiazol-5-yl)-3-[2-(dimethylamino)phenyl]but-2-enedioic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H15N3O4S
assistant