You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 7-acetyl-N-[(3,4-dimethoxyphenyl)methyl]-6,8-dihydro-5H-2,7-naphthyridine-4-carboxamide into molecular formula.
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C20H23N3O4
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