You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 5-(6,7-dihydro-4H-thieno[3,2-c]pyridin-5-yl)-2,2-dimethyl-5-(2-methylphenyl)pentanoic acid by IUPAC nomenclature, provide its molecular formula.
user
C21H27NO2S
assistant