modn :: Integer -> Integer
modn m = m `mod` 1000000007


kkp :: Int -> Integer -> Integer -> Integer -> Integer
kkp 0 a b c = modn (a + b + c)
kkp i a b c = kkp (i - 1) c a (modn (a + b))

solve :: Int -> Integer
solve n = kkp (n - 1) 1 0 0

main = readLn >>= print . solve