You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named N-benzyl-N-[2-[4-(1-methylpyrazol-4-yl)-3-oxopiperazin-1-yl]ethyl]methanesulfonamide by IUPAC nomenclature, provide its molecular formula.
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C18H25N5O3S
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