You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[2-chloro-5-(2-chloro-4-nitrophenyl)phenoxy]-2-(3,4-dichlorophenyl)-3-oxopentanenitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H14Cl4N2O4
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