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 [4-[[(1R,2S,4S)-2-bicyclo[2.2.1]hept-5-enyl]methyl]piperazin-4-ium-1-yl]-(4-methoxyphenyl)methanone .
user
C20H27N2O2+
assistant