object Main extends App {
  val n: Int = scala.io.StdIn.readInt()

  def stream(n: Int): Stream[Int] = Stream.cons(n, stream(n + n))

  // 0,1,2,4 ..
  val mugen: Stream[Int] = (0 #:: stream(1)).map(_ * 2)

  val targetValue = mugen.find(_ > n - 1)

  println(if (n <= 1) 0 else mugen.indexOf(targetValue.get))
}