You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 3,6-dimethyl-7-(4-methylnaphtho[2,3-b][1]benzofuran-3-yl)thieno[2,3-c]pyridin-6-ium;6-methyl-7-(4-methylnaphtho[2,3-b][1]benzofuran-3-yl)-3-propan-2-ylthieno[2,3-c]pyridin-6-ium;2,3,6-trimethyl-7-(4-methylnaphtho[2,3-b][1]benzofuran-3-yl)thieno[2,3-c]pyridin-6-ium is given. What is its corresponding molecular formula?
user
C81H66N3O3S3+3
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