You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 2-(2,8-diazaspiro[3.5]nonan-2-yl)-5-[2-(trifluoromethyl)pyridin-3-yl]sulfanyl-3H-imidazo[4,5-b]pyrazine into molecular formula.
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C18H18F3N7S
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