You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 2-(3-chloro-4-fluorophenyl)-5-(3,3-dimethylbutanoyl)spiro[4,6-dihydropyrazolo[1,5-a]pyrazine-7,3'-oxetane]-3-carboxamide is given. What is its corresponding molecular formula?
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C21H24ClFN4O3
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