You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[4-[[4-[(E)-2-(aminomethyl)-3-fluoroprop-2-enoxy]phenyl]sulfonylmethyl]piperidin-1-yl]-4-fluoro-2-methylidenebutan-1-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H28F2N2O4S
assistant