c, d = gets.split.map(&:to_f)
if 42 * d - 14 * c >= 0 && 20 * c - 8 * d >= 0 
    p (34 * d + 6 * c) * 1000 / 13
else
    p [[4 * d, 4 * c / 3].min * 1000, [7 * c / 2, 7 * d / 5].min * 2000].max
end