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 tert-butyl N-[2-[2-(2-chloro-4-fluorobenzoyl)-5-oxopyrrolidin-1-yl]ethyl]carbamate is given. What is its corresponding molecular formula?
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C18H22ClFN2O4
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