module Athena3
  def self.solve(a)
    ax, ay, bx, by, cx, cy = a
    mx = 0
    ope([ax, ay]).each do |p0|
      ope([bx, by]).each do |p1|
        ope([cx, cy]).each do |p2|
          mx = [mx, area(p0, p1, p2)].max
        end
      end
    end
    mx
  end
  def self.ope(p)
    [
      [p[0]+1, p[1]],
      [p[0]-1, p[1]],
      [p[0], p[1]+1],
      [p[0], p[1]-1]
    ]
  end
  def self.area(a, b, c)
    x0 = b[0] - a[0]
    y0 = b[1] - a[1]
    x1 = c[0] - a[0]
    y1 = c[1] - a[1]
    (x0 * y1 - y0 * x1).abs / 2.0
  end
end

puts Athena3.solve(gets.chomp.split(/\s+/).map(&:to_i))