You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 2-[2-amino-4-(4-fluorophenyl)-3-methylimidazol-1-ium-1-yl]-1-(4-bromophenyl)ethanone into molecular formula.
user
C18H16BrFN3O+
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