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 4-ethyl-7-[(Z)-4-methoxy-3-methyl-2-(2-methylpropylideneamino)but-2-enyl]pyrrolo[2,3-d]pyrimidin-2-amine into molecular formula.
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C18H27N5O
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