def side(p1, p2, pp)
  return (p2[0] - p1[0]) * (pp[1] - p1[1]) - (p2[1] - p1[1]) * (pp[0] - p1[0])
end

def inside_triangle?(data)
  p1 = data.slice(0, 2)
  p2 = data.slice(2, 2)
  p3 = data.slice(4, 2)
  pp = data.slice(6, 2)

  point_a = side(p1, p2, pp)
  point_b = side(p2, p3, pp)
  point_c = side(p3, p1, pp)

  (point_a > 0 && point_b > 0 && point_c > 0) || (point_a < 0 && point_b < 0 && point_c < 0)
end

while line = gets
  puts inside_triangle?(line.split(" ").map(&:to_f)) ? "YES" : "NO"
end