You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule (1S,5R)-3-[(4-acetyl-1-methylpyrrol-2-yl)methyl]-6-(pyridin-2-ylmethyl)-3,6-diazabicyclo[3.2.2]nonan-7-one into molecular formula.
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C21H26N4O2
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