You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(4E)-2-chloro-4-[(1E)-1-hydroxybuta-1,3-dienyl]iminocyclohexa-2,5-dien-1-ylidene]isoindol-2-ium-1,3-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H12ClN2O3+
assistant