You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 1-(2,4-dichlorophenyl)-4-methyl-5-(5-propyl-2,3-dihydrothiophen-2-yl)pyrazole-3-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
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C20H22Cl2N2O2S
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