You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule (2Z)-2-[1-(5-ethenyl-3-ethynyl-4-methylidenepyridin-1-id-2-yl)prop-2-enylidene]-3,4,4a,5,6,7-hexahydro-1H-pyrrolo[1,2-c]pyrimidin-2-ium ?
user
C20H23N3
assistant