You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name N-[(4-chloro-2,6-difluorophenyl)methyl]-4-[[2-(4-chloro-3-fluorophenoxy)acetyl]amino]-2-methylidenebutanamide into its molecular formula.
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C20H17Cl2F3N2O3
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