You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[3-[(4R,5R,6R)-2-amino-5-fluoro-4,6-dimethyl-5,6-dihydro-1,3-thiazin-4-yl]-4-fluorophenyl]-5-(difluoromethyl)pyrazine-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H17F4N5OS
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