You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5R)-7-[(2,2-dimethyl-3H-1-benzofuran-7-yl)sulfonyl]-2-oxa-7-azaspiro[4.4]nonane is the IUPAC name of a molecule. Please give its molecular formula.
user
C17H23NO4S
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