You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-[(3-oxo-4H-1,4-benzoxazin-6-yl)sulfonyl]-N-phenylpiperidine-3-carboxamide by IUPAC nomenclature, provide its molecular formula.
user
C20H21N3O5S
assistant