You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
propan-2-yl 3-[[4-chloro-1-(2,5-dichlorophenyl)-2,5-dioxopyrrol-3-yl]amino]benzoate is the IUPAC name of a molecule. Please give its molecular formula.
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C20H15Cl3N2O4
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