You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-O-tert-butyl 1-O-ethyl 6-(3,4-dichlorophenyl)-5-fluoro-3-azabicyclo[4.1.0]heptane-1,3-dicarboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H24Cl2FNO4
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