modulo :: Int
modulo = 1000000007
{-# INLINE modulo #-}

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

solver :: Int -> Int
solver n = iter n (0, 1, 0)
  where
    iter :: Int -> (Int, Int, Int) -> Int
    iter 1 (a, b, c) = mod (a + b + c) modulo
    iter i (a, b, c) = iter (i - 1) (b, c, mod (a + b) modulo)