You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 2-[6-methyl-3-oxo-4-[(4,5,7-trifluoro-1,3-benzothiazol-2-yl)methyl]-1,4-benzothiazin-2-yl]acetate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H17F3N2O3S2
assistant