You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(3,4-dimethoxyphenyl)methyl]-2-[(4R)-4-methyl-2,5-dioxo-4-phenylimidazolidin-1-yl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
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C21H23N3O5
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