You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[4-[(3S)-3-[2-(3-fluorophenyl)ethylamino]-2,5-dioxopyrrolidin-1-yl]phenyl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H20FN3O3
assistant