You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-butyl-3-[[3-(3-methoxyphenyl)-1,2,4-oxadiazol-5-yl]methyl]-5-methylimidazolidine-2,4-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H22N4O4
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