import scala.io.StdIn.readInt

@main
def yuki44(): Unit =
  val dp: List[Long] = LazyList.unfold((1L, 1L)) { case (a, b) =>
    if a < 0 then
      None
    else
      Some((a, (b, a + b)))
  }.toList
  val n = readInt
  println(dp(n))