Hackerran angry children in scala

Angry Children.scala

object Solution{
  def main(args: Array[String]) ={
    val lines = io.Source.stdin.getLines.drop(1).toList
    val k = lines(0).toInt
    val kNumsSets = lines.drop(1).map( l => BigInt(l)).sorted.toArray
    var unfairness = kNumsSets.last
    for(i <- 0 to kNumsSets.size -k -1){
      val diff= kNumsSets(i + k-1 ) - kNumsSets(i)
      if( diff < unfairness) unfairness = diff
    }
    println(unfairness)
  }
}