You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (4aR,8aS)-6-[2-methyl-3-[[2-methyl-4-(trifluoromethoxy)phenyl]methoxy]azetidine-1-carbonyl]-4,4a,5,7,8,8a-hexahydropyrido[4,3-b][1,4]oxazin-3-one by IUPAC nomenclature, provide its molecular formula.
user
C21H26F3N3O5
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