You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (5S)-7-benzyl-5-methyl-3-[5-(2-methylpropyl)-1,2-oxazol-3-yl]-5,8-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-6-one into its molecular formula.
user
C20H23N5O2
assistant