object Main extends App {
  val in = scala.io.Source.stdin.getLines.toSeq
  val ls = in.map(_.toInt)
  val K = ls.last
  val list = ls.dropRight(1)
  val min = list.min
  val max = list.max
  val b = (max - min) <= K
  val ret = if(b) "Yay!" else ":("
  println(ret)
}
