You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule 3-[(4-phenyl-6,7-dihydro-4H-thieno[3,2-c]pyridin-5-yl)methyl]-1,3-diazaspiro[4.4]nonane-2,4-dione into molecular formula.
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C21H23N3O2S
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