You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[3-methyl-4-(3-pyridin-3-yl-1,2,4-oxadiazol-5-yl)pyrrolidin-1-yl]-2-phenylsulfanylethanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H20N4O2S
assistant