{-# LANGUAGE BangPatterns #-}
data Matrix a = Matrix2x2 !a !a !a !a

matMul :: Matrix Integer -> Matrix Integer -> Matrix Integer
matMul (Matrix2x2 a b c d) (Matrix2x2 x y z w)
    = Matrix2x2 (a * x + b * z) (a * y + b * w)
                (c * x + d * z) (c * y + d * w)

matPower :: Matrix Integer -> Int -> Matrix Integer
matPower _ 0 = Matrix2x2 1 0 0 1
matPower m i = loop m m (i - 1)
    where
        loop acc !_ 0 = acc
        loop acc m 1  = acc `matMul` m
        loop acc m i  = case i `divMod` 2 of
                            (j, 0) -> loop acc (m `matMul` m) j
                            (j, _) -> loop (acc `matMul` m) (m `matMul` m) j


main :: IO ()
main = readLn >>= print . solve

solve :: Int -> Integer
solve m = let (Matrix2x2 a b c d) = (Matrix2x2 1 1 1 0) `matPower` (m + 1)
          in b