You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S)-N-[(4-ethyl-1,2,4-triazol-3-yl)methyl]-2-(2-phenylethyl)morpholine-4-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H25N5O2
assistant