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 (3E)-5-bromo-3-[(3,4-dimethylthieno[2,3-b]thiophen-5-yl)methylidene]-4-methyl-1H-indol-2-one is given. What is its corresponding molecular formula?
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C18H14BrNOS2
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