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 (5aR,9aR)-8-methyl-4-phenyl-3,5a,6,7,9,9a-hexahydro-2H-pyrido[4,3-f][1,4]oxazepin-5-one ?
user
C15H20N2O2
assistant