m :: Int
m = 1000000007

-- based on https://wiki.haskell.org/Memoization
kenkenpa :: Int -> Int
kenkenpa = (!!) (map ken [1 ..]) . subtract 1
    where
        ken 1 = 1
        ken 2 = 2
        ken 3 = 2
        ken n = flip mod m $ kenkenpa (n - 3) + kenkenpa (n - 2)

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