You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-ethyl-N-[4-(4-ethyl-3-oxo-1,4-benzoxazin-6-yl)-1,3-thiazol-2-yl]butanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H23N3O3S
assistant