You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (5E)-5-[[1-(2,4-difluorophenyl)-2,5-dimethylpyrrol-3-yl]methylidene]-4-hydroxy-2-methylpyrrole-3-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20F2N2O3
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