You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-methoxy-N-[[1-(6-methyl-4,5,7,8-tetrahydrothieno[2,3-d]azepine-2-carbonyl)pyrrolidin-2-yl]methyl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H27N3O3S
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