You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl 2-[[2-[[(1S)-1-(4-chlorophenyl)ethyl]amino]acetyl]amino]-5,6-dihydro-4H-cyclopenta[b]thiophene-3-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H21ClN2O3S
assistant