You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S)-2-[[(2S)-2-amino-4-methylsulfanylbutanoyl]amino]-3-[[(E)-4-methoxy-4-oxobut-2-enoyl]amino]propanoic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C13H21N3O6S
assistant