You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 1-ethyl-2-[2-(4-methylphenyl)propyl]-3-[1-(2-methylsulfonylethyl)piperidin-4-yl]guanidine;hydroiodide into molecular formula.
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C21H37IN4O2S
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