You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(2R,3R)-3-amino-2-(bromomethyl)-4-oxoazetidin-1-yl]-2-ethanethioyloxyacetic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C8H11BrN2O4S
assistant