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-(3-ethoxyspiro[3.3]heptan-1-yl)-3-ethyl-2-[2-(3-methylpyridin-4-yl)ethyl]guanidine;hydroiodide into molecular formula.
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C20H33IN4O
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