You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4aR,6R,8aS)-8a-[2-fluoro-5-(2-fluoropyridin-3-yl)phenyl]-6-(trifluoromethyl)-4a,5,6,8-tetrahydro-4H-pyrano[3,4-d][1,3]thiazin-2-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H16F5N3OS
assistant