object Main extends App {
  def crossProduct(p1: (Double, Double, Double),
                   p2: (Double, Double, Double)): (Double, Double, Double) = {
    (
      p1._3 * p2._2 - p1._2 * p2._3,
      p1._1 * p2._3 - p1._3 * p2._1,
      p1._2 * p2._1 - p1._1 * p2._2
    )
  }

  Stream
    .continually(readLine)
    .takeWhile(_ != null)
    .map(_.split(" ").map(_.toDouble) match {
      case Array(x1, y1, x2, y2, x3, y3, xp, yp) =>
        val (ab, ap, bc, bp, ca, cp) = (
          (x2 - x1, y2 - y1, 0.0),
          (xp - x1, yp - y1, 0.0),
          (x3 - x2, y3 - y2, 0.0),
          (xp - x2, yp - y2, 0.0),
          (x1 - x3, y1 - y3, 0.0),
          (xp - x3, yp - y3, 0.0)
        )
        Seq((ab, ap), (bc, bp), (ca, cp)).map { case (p1, p2) => crossProduct(p1, p2) }
    })
    .map(_.map(_._3 > 0))
    .map(zIsPositives => zIsPositives.forall(_ == zIsPositives.head))
    .foreach(isInner => println(if (isInner) "YES" else "NO"))
}

