You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-(5-chloro-2-methylphenyl)-2-(4-oxo-3,5-dihydro-2H-1,5-benzoxazepin-3-yl)acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H17ClN2O3
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