You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule 7-[(3S)-4-(2-amino-6-methylpyrimidin-4-yl)-1,4-oxazepan-3-yl]-6-chloro-4H-1,4-benzoxazin-3-one ?
user
C18H20ClN5O3
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