You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name N-(7-bromoisoquinolin-3-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'-4H-1,3-oxazole]-2'-amine into its molecular formula.
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C18H19BrN4O
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