You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule 2-[2-amino-4-(4-bromophenyl)-3-methylimidazol-1-ium-1-yl]-1-(3,4-dichlorophenyl)ethanone;bromide ?
user
C18H15Br2Cl2N3O
assistant