You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule N-(5-cyclopropyl-3-methyl-1,2-oxazol-4-yl)-2-[(3R)-2',5'-dioxospiro[1,2-dihydroindene-3,4'-imidazolidine]-1'-yl]acetamide into molecular formula.
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C20H20N4O4
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