You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (E)-3-[5-[[(3R)-1-(pyridin-4-ylmethyl)piperidin-3-yl]amino]pyrazin-2-yl]prop-2-enoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H25N5O2
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