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

solve :: Int -> Integer
solve n = solve' 1 n (1, 0, 0)
    where solve' :: Int -> Int -> (Integer, Integer, Integer) -> Integer
          solve' i n (a, aa, ab)
            | i == n = (a + aa + ab) `mod` (10 ^ 9 + 7)
            | otherwise = solve' (i + 1) n (ab, a, a + aa)