You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-(6,7-dihydro-4H-thieno[3,2-c]thiopyran-4-carbonylamino)-4-propan-2-yloxybenzoic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H19NO4S2
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