import scala.math._

object Main {
  def main(args: Array[String]) {
    val sc = new java.util.Scanner(System.in)
    val n = sc.nextInt

    val xs = (1 to n).map { _ => sc.nextInt }.toArray.sorted
    if (xs.size % 2 == 0) {
      val a = xs(xs.size / 2 - 1)
      val b = xs(xs.size / 2)
      println((a + b) / 2.0)
    }
    else {
      println(xs(xs.size/2))
    }
  }
}