You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(5,6-difluoro-1H-indol-3-yl)-3-[5-[4-fluoro-4-(fluoromethyl)piperidin-1-yl]-6-methylpyrazin-2-yl]urea is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H20F4N6O
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