def main():
  dp = []
  mod = 10**9 + 7
  N = int(input())

  for n in range(N):
    if n == 0:
      dp.append(1)
    elif n == 1 or n == 2:
      dp.append(2)
    else:
      dp.append(dp[n-3]+dp[n-2])

  print(dp[-1] % mod)

main()