You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(1R,2S)-2-(2-chlorophenyl)cyclopropyl]-[(3R)-3-(1H-pyrazol-5-yl)piperidin-1-yl]methanone is the IUPAC name of a molecule. Please give its molecular formula.
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C18H20ClN3O
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