You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R,5R,6S)-3,3-dimethyl-6-(2-methylpropoxycarbonylamino)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C13H20N2O5S
assistant