You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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2-[1,2-dichloro-2-[[1,2-dichloro-2-(1,3-dioxoisoindol-2-yl)ethyl]amino]ethyl]isoindole-1,3-dione is the IUPAC name of a molecule. Please give its molecular formula.
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C20H13Cl4N3O4
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