object Main extends App {
  val sc = new java.util.Scanner(System.in)
  val s = sc.next()
  val ansS = s.inits.toList.tail.find{ t =>
    val l = t.length
    l % 2 == 0 && t.take(l/2) == t.drop(l/2)
  }.get
  println(ansS.length)
}
