You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(8aR)-8a-(4-chlorophenyl)-1,2,3,4,7,8-hexahydropyrrolo[1,2-a]pyrimidin-6-one is the IUPAC name of a molecule. Please give its molecular formula.
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C13H15ClN2O
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