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 2-(4-methylsulfonylphenyl)-1-[2-[2-(2-pyrazin-2-yl-1,3-thiazol-4-yl)acetyl]pyrazolidin-1-yl]ethanone into molecular formula.
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C21H21N5O4S2
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