You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 4-[(2S)-2-(3,4-dihydro-2H-1,5-benzodioxepin-7-ylsulfanyl)propanoyl]-1,3-dihydroquinoxalin-2-one into molecular formula.
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C20H20N2O4S
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