import java.util.Scanner

object Problem275 {
  def main(args: Array[String]) {
    val sc = new Scanner(System.in)
    val n = sc.nextInt()
    val a = Seq.fill(n)(sc.nextInt()).sorted

    val result: Double =
      if (n % 2 == 0) {
        (a(n / 2 - 1) + a(n / 2)).toDouble / 2
      } else {
        a(n / 2)
      }

    println(result)
  }
}