You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 4-[2-[(2R)-2-[(Z)-3-hydroxy-4-phenylbut-2-enyl]-6-oxopiperidin-1-yl]ethylsulfanyl]butanoic acid into its molecular formula.
user
C21H29NO4S
assistant