You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name N-[3-[(4S)-2-amino-4-methyl-6-propan-2-yl-1,3-thiazin-4-yl]-4-fluorophenyl]-5-methoxypyrazine-2-carboxamide into its molecular formula.
user
C20H22FN5O2S
assistant