import Control.Monad
import Data.Array.ST
import Data.Array.Unboxed

m :: Int
m = 10 ^ 9 + 7

kenTable :: Int -> UArray Int Int
kenTable n = runSTUArray $ do
    t <- newArray_ (1, max 3 n)
    writeArray t 1 1
    writeArray t 2 2
    writeArray t 3 2
    forM_ [4 .. n] $ \i -> do
        term1 <- readArray t $ i - 2
        term2 <- readArray t $ i - 3
        writeArray t i $ flip mod m $ term1 + term2
    return t

ken :: Int -> Int
ken n = (! n) $ kenTable n

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