You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(1R,4S)-4-(3,4-dichlorophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-1-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H19Cl2N
assistant