You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
7-[4-(6-chloropyrazin-2-yl)-3-methylpiperazin-1-yl]-1-(2,4-difluorophenyl)-6-fluoro-4-oxoquinoline-3-carboxylic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C25H19ClF3N5O3
assistant