You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule (6S,7S)-7-ethyl-2-nitro-N-[[4-(trifluoromethoxy)phenyl]methyl]-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazin-6-amine into molecular formula.
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C16H17F3N4O4
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