You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name ethyl 2-[[4-(5-chloro-1-methyl-6-oxopyridin-3-yl)-3-oxobutyl]amino]-2-(3-chlorophenyl)acetate into its molecular formula.
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C20H22Cl2N2O4
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