You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-pyridin-3-ylacetonitrile;(Z)-2-pyridin-3-yl-3-pyridin-4-ylprop-2-enenitrile by IUPAC nomenclature, provide its molecular formula.
user
C20H15N5
assistant