You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[1-(3,4-dichlorophenyl)ethyl]-2-(2,3-dihydro-1,4-benzodioxin-6-ylsulfanyl)acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H17Cl2NO3S
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