main = do
  n <- readLn :: IO Int
  print $ solve n

m :: Int
m = 1000000007

solve :: Int -> Int
solve n = rec 1 0 1 0
    where rec i a b c
            | i == n = (a + b + c) `mod` m
          rec i a b c = rec (i+1) b c ((a + b) `mod` m)