You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Name the molecular formula for the molecule established as 1-[(Z)-1-(5-nitrofuran-2-yl)-2-(5-phenylfuran-2-yl)ethenyl]pyridin-1-ium using the IUPAC nomenclature.
user
C21H15N2O4+
assistant