You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Translate the chemical IUPAC name N-[(2-chlorophenyl)methyl]-2',5'-dioxospiro[7,8-dihydro-5H-naphthalene-6,4'-imidazolidine]-2-carboxamide into its molecular formula.
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C20H18ClN3O3
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