def mergeMatch(limit: Int)(a: Seq[Int], b: Seq[Int]): Int = {

  def mergeRec(limit: Int, a: Seq[Int], b: Seq[Int], acc: Int): Int = {
    (a,b) match {
      case (_, Nil) | (Nil, _) => acc
      case (x +: xs, y +: ys) => if(Math.abs(x-y) < limit) mergeRec(limit, xs, ys, acc+1) else {
        if(x < y) mergeRec(limit, xs, y +: ys, acc)
        else mergeRec(limit, x +: xs, ys, acc)
      }
    }
  }

  mergeRec(limit, a, b, 0)
}