You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (3S,6R,7R,9aS)-6-(4-bromophenyl)-3,7-dimethyl-4,6,7,8,9,9a-hexahydro-3H-pyrido[2,1-c][1,4]oxazin-1-one into its molecular formula.
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C16H20BrNO2
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