def gridlandMetro(n: Int, m: Int, k: Int, track: Array[Array[Int]]): Long = {
    var ans = 1L * n*m
    track.groupBy(_(0)).values.foreach{ x =>
        x.sortInPlaceBy{_(1)}
        var (l,r) = (x.head(1), x.head(2)) 
        x.tail.foreach { t => (t(1),t(2)) match {
              case (a,b) if a > r =>
                ans -= (r - l + 1)
                l = a
                r = b
              case (_,b) => r = r.max(b)
            }
        }
        ans -= (r - l + 1)
    }
  ans
}