You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 1-[[1-(4-chlorophenyl)pyrazol-4-yl]methyl]-3-[(6-imidazol-1-ylpyridin-3-yl)methyl]urea into its molecular formula.
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C20H18ClN7O
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