You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 19,19-dimethyl-17-thia-15-azapentacyclo[12.7.0.02,7.08,13.016,20]henicosa-1(21),2,4,6,8,10,12,14,16(20)-nonaene is given. What is its corresponding molecular formula?
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C21H17NS
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