You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name ethyl 5-(4-chlorophenyl)-2-methyl-1-[2-[(2E)-2-[(5-nitrofuran-2-yl)methylidene]hydrazinyl]-2-oxoethyl]pyrrole-3-carboxylate into its molecular formula.
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C21H19ClN4O6
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