val lines = Source
        .fromResource("doc-topics-new.txt")
        .getLines
        .toList
        .drop(1) match {
        case x :: xs => x.split(" ").drop(2).mkString(" ") :: xs
      }

Warning:(81, 14) match may not be exhaustive.
It would fail on the following input: Nil
        .drop(1) match {