You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
sodium;(2S,3S)-3-[[(2S)-1-(3-methylsulfanylpropylamino)-1-oxo-3-phenylpropan-2-yl]carbamoyl]oxirane-2-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C17H21N2NaO5S
assistant