You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(5-amino-2,4-difluorophenyl)-7-[(3S,4S)-3-amino-4-hydroxypyrrolidin-1-yl]-6,8-difluoro-4-oxoquinoline-3-carboxylic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H16F4N4O4
assistant