3-Quinolinecarboxylic acid, 1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-

1-(2,4-Difluorophenyl)-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid