{-# OPTIONS_GHC -fexcess-precision #-}
-- !!! the ultra-notorious "nfib 30" does w/ Floats
--
import System

main = do
    [arg] <- getArgs
    print $ nfib $ read arg

nfib :: Double -> Double
nfib n = if n <= 1 then 1 else nfib (n-1) + nfib (n-2) + 1