You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[3-[(5R,9R)-7-amino-2,2-difluoro-5,9-dimethyl-6-thia-8-azaspiro[3.5]non-7-en-9-yl]-4-fluorophenyl]-5-(fluoromethoxy)pyrazine-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H21F4N5O2S
assistant