You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[4-[3-(1-methylpyrrolidin-2-yl)-5,6,8,9-tetrahydro-[1,2,4]triazolo[4,3-d][1,4]diazepine-7-carbonyl]phenyl]acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H26N6O2
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