n = int(input())
dp = [0]*3
for i in range(n):
    if i == 0:
        dp[0]=1
        continue
    dp[0], dp[1], dp[2] = dp[2]%(10**9+7), dp[0]%(10**9+7), (dp[0]+dp[1])%(10**9+7)
print(sum(dp)%(10**9+7))