import scala.collection.mutable
val x = 4
val y = 15
val arr = Array(5, 5, 5, 5, 6, 7, 9, 10, 10, 10, 11, 13)
val missingValues = (x to y).toSet.diff(arr.toSet)
println("missingValues: " + missingValues)
/*
run:
missingValues: HashSet(14, 12, 8, 4, 15)
*/