You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule N-[[(3S,3aS)-7-(4,4-difluoropiperidin-1-yl)-8-fluoro-1-oxo-3a,4-dihydro-3H-[1,3]oxazolo[4,3-c][1,4]benzoxazin-3-yl]methyl]acetamide .
user
C18H20F3N3O4
assistant