You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 2-(1-butyl-4,5-dimethylimidazol-2-yl)sulfanyl-N-(5-chloro-2-cyanophenyl)acetamide is given. What is its corresponding molecular formula?
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C18H21ClN4OS
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