You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (E)-3-[3-methyl-1-[4-(trifluoromethyl)phenyl]pyrazol-4-yl]but-2-enoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C17H17F3N2O2
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