You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 1-[(1R,3S)-3-[[2-(5-chloro-1H-pyrrolo[2,3-b]pyridin-3-yl)-5-fluoropyrimidin-4-yl]amino]cyclohexyl]-3-methylimidazolidin-2-one into its molecular formula.
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C21H23ClFN7O
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