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 N-[(4-chlorophenyl)methyl]-2-methyl-1-(3-methylsulfanylphenyl)-4-methylsulfonyl-6-oxopiperazine-2-carboxamide is given. What is its corresponding molecular formula?
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C21H24ClN3O4S2
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