You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule 2-[(3S)-4-(4-fluorophenyl)-3-methylpiperazin-1-yl]-2-oxo-N-(2-oxo-3H-1-benzofuran-6-yl)acetamide ?
user
C21H20FN3O4
assistant