import strutils, math var N = stdin.readLine.parseInt proc fibo(n : int) : int = var m = n.toFloat var t1 = pow(((1 + pow(5, 0.5)) / 2), m) t2 = pow(((1 - pow(5, 0.5)) / 2), m) result = round((t1 - t2) / pow(5, 0.5)).toInt echo fibo(N+1)