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

solve :: Int -> Int
solve n = solve' 1 n (1, 0, 0)
    where reduce :: Int -> Int
          reduce a = a `mod` (1000000007)

          solve' :: Int -> Int -> (Int, Int, Int) -> Int
          solve' i x (a, aa, ab)
            | i == x = reduce (a + aa + ab)
            | otherwise = solve' (i + 1) x (ab, a, reduce (a + aa))