You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (E)-1-(2-chloro-5-nitrophenyl)-N-[4-(9H-fluoren-9-yl)piperazin-4-ium-1-yl]methanimine by IUPAC nomenclature, provide its molecular formula.
user
C24H22ClN4O2+
assistant