Gravar-mail: 4-[4-(4-Fluoro­phen­yl)-2-methyl-5-oxo-2,5-dihydro­isoxazol-3-yl]-1-methyl­pyridinium iodide–4-[3-(4-fluoro­phen­yl)-2-methyl-5-oxo-2,5-dihydro­isoxazol-4-yl]-1-methyl­pyridinium iodide (0.6/0.4)