You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 4-[(3,5-difluorophenyl)methyl]-2-methyl-3-oxo-N-(pyrazin-2-ylmethyl)-1,4-benzothiazine-6-carboxamide into its molecular formula.
user
C22H18F2N4O2S
assistant