You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[4-[(E)-3-[2-amino-5-[(1R)-1-(3,5-dichloropyridin-4-yl)ethoxy]phenyl]-3-iminoprop-1-enyl]pyrazol-1-yl]ethanol The above is the IUPAC name of a molecule. Write its molecular formula.
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C21H21Cl2N5O2
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