You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R)-N-(2,4-dichlorophenyl)-2-(4-pyridin-1-ium-2-ylpiperazin-1-ium-1-yl)propanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H22Cl2N4O+2
assistant