You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
6-cyano-N-[(1S)-1-(3,4-difluorophenyl)ethyl]-3-[[4-(2-oxo-1,7a-dihydroimidazo[4,5-b]pyridin-6-yl)phenyl]methylamino]pyrazine-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C27H20F2N8O2
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