You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named (4S)-1-(4-ethoxyphenyl)-4-(3-pyridin-2-yl-1,2,4-oxadiazol-5-yl)pyrrolidin-2-one is given. What is its corresponding molecular formula?
user
C19H18N4O3
assistant