You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3S,4S)-4-[4-[4-[(2S)-butan-2-yl]phenyl]sulfonylpiperazin-1-yl]-1,1-dioxothiolan-3-ol is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H28N2O5S2
assistant