You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(1Z)-4-[4-(dimethylamino)phenyl]-1-(1-ethylbenzotriazol-1-ium-2-yl)buta-1,3-dien-2-ol is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H23N4O+
assistant