You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule [4-[[3-(4-chlorophenyl)-1,2,4-oxadiazol-5-yl]methyl]piperazin-1-yl]-(3-methylsulfonylphenyl)methanone into molecular formula.
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C21H21ClN4O4S
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