You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 1-[2-(1-benzothiophen-2-yl)-2-hydroxyethyl]-2-methyl-3-[(3-nitrophenyl)methyl]guanidine;hydroiodide by IUPAC nomenclature, provide its molecular formula.
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C19H21IN4O3S
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