You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule identified by ethyl N-[(2R)-1-(3-cyclopropyl-6,8-dihydro-5H-[1,2,4]triazolo[4,3-a]pyrazin-7-yl)-1-oxo-3-phenylpropan-2-yl]carbamate ?
user
C20H25N5O3
assistant