You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(2',4-dioxospiro[3H-1,3-benzoxazine-2,5'-azepane]-1'-yl)-N-(2-methylbutan-2-yl)propanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H29N3O4
assistant