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For the molecule named 1-ethyl-2-[[4-fluoro-3-(hydroxymethyl)phenyl]methyl]-3-[[4-methyl-2-(2,2,2-trifluoroethoxy)phenyl]methyl]guanidine;hydroiodide by IUPAC nomenclature, provide its molecular formula.
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C21H26F4IN3O2
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