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 4-[1-(2,4-dioxo-3-propan-2-yl-1,3,7-triazaspiro[4.4]nonan-7-yl)ethyl]benzonitrile into its molecular formula.
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C18H22N4O2
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