fun main(args : Array<String> ) {
  val a   = readLine()!!.toLong()
  val b   = 1000000001L
  val ans = (1..a/b).map { x ->
    val c1 = (x * b).toString().toList()
    val c2 = c1.reversed()
    c1.zip(c2).all { xy ->
      val (x,y) = xy
      x == y
    }
  }.count { x -> x == true }
  println( ans )
}