You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 9-(azet-2-yl)-11-[(2Z,4Z)-hexa-2,4-dienylidene]-3-phenyl-1,2-dihydrobenzo[a]carbazol-11-ium .
user
C31H25N2+
assistant