You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-acetyl-N-[3-(3-methyl-1,2,4-oxadiazol-5-yl)phenyl]-2,3-dihydroindole-5-sulfonamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H18N4O4S
assistant