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 3-amino-N-[[1-[(Z)-but-2-en-2-yl]-4-(2,5-difluorophenyl)piperidin-4-yl]methyl]pyrazine-2-carboxamide is given. What is its corresponding molecular formula?
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C21H25F2N5O
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