You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule 6-[1-hydroxy-2-(5H-imidazo[5,1-a]isoindol-5-yl)ethyl]-4H-1,4-benzoxazin-3-one into molecular formula.
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C20H17N3O3
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