You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(E)-N-[5-methyl-2-(1-methylbenzimidazol-2-yl)pyrazol-3-yl]-3-phenylprop-2-enamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H19N5O
assistant