You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 3-[(E)-2-(3-prop-2-enyl-1,3-benzothiazol-3-ium-2-yl)ethenyl]chromen-4-one is given. What is its corresponding molecular formula?
user
C21H16NO2S+
assistant