You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-[(4-chlorophenyl)methylamino]-2-oxoethyl] 4-chloro-2-(2-oxopyrrolidin-1-yl)benzoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H18Cl2N2O4
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