import strutils, math

const M = 10 ^ 9 + 7
let N = stdin.readLine.parseInt
var dp = newSeq[tuple[k1, k2, p: int]](1)

dp[0].k1 = 1
for i in 1 ..< N:
  let
    K1 = dp[0].p
    K2 = dp[0].k1
    P = (dp[0].k1 + dp[0].k2) mod M
  dp.add (K1, K2, P)
  dp.delete 0

echo (dp[^1].k1 + dp[^1].k2 + dp[^1].p) mod M