You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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8-bromo-4-[[4-(pyrrolidin-1-ylmethyl)phenyl]iminomethyl]-2,4-dihydro-1H-isoquinolin-3-one is the IUPAC name of a molecule. Please give its molecular formula.
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C21H22BrN3O
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