You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-oxo-2-(thiophene-2-carbonylamino)ethyl] 2-[(4-acetylphenyl)sulfonyl-methylamino]acetate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H18N2O7S2
assistant