You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-[(1-cyanocyclopentyl)amino]-2-oxoethyl] 4-oxo-4-(5-phenyl-3,4-dihydropyrazol-2-yl)butanoate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H24N4O4
assistant