You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-chloro-N-[3-(4-fluorophenyl)prop-2-enyl]-N-(1-hydroxy-4-methylpentan-2-yl)benzenesulfonamide is the IUPAC name of a molecule. Please give its molecular formula.
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C21H25ClFNO3S
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