object Main extends App {
	def dist(pos: Seq[(Int, Int)]): Double = {
		val x = pos(0)._1 - pos(1)._1
		val y = pos(0)._2 - pos(1)._2
		scala.math.sqrt(x * x  + y * y)
	}
	
	val sc = new java.util.Scanner(System.in)
	val n = sc.nextInt
	val p = List.fill(n)((sc.nextInt, sc.nextInt))
	
	println(p.combinations(2).map(dist(_)).max / 2.0)
}