You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Translate the chemical IUPAC name (5R,7S)-7-(4-methoxyphenyl)-5-phenyl-4,5,6,7-tetrahydro-[1,2,4]triazolo[1,5-a]pyrimidin-2-amine into its molecular formula.
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C18H19N5O
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