You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 3-[4-methyl-5-(phenanthridin-6-ylmethylsulfanyl)-1,2,4-triazol-3-yl]thiolane 1,1-dioxide into its molecular formula.
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C21H20N4O2S2
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