You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[4-ethyl-5-[(2S)-1-oxo-1-(4-phenylpiperazin-1-yl)propan-2-yl]sulfanyl-1,2,4-triazol-3-yl]propanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H28N6O2S
assistant