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 (2S,3R,4S,5S,6S)-2-[4-chloro-3-[(5-pyrazin-2-yl-1,3,4-thiadiazol-2-yl)methyl]phenyl]-6-(hydroxymethyl)-5-methyloxane-3,4-diol is given. What is its corresponding molecular formula?
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C20H21ClN4O4S
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