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-[2-(6,7-dihydro-4H-thieno[3,2-c]pyridin-5-yl)-2-oxoethyl]-2-methyl-3-(5-methylhexan-2-yl)guanidine;hydroiodide into molecular formula.
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C18H31IN4OS
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