n = int(input())
dp = [[0]*4 for i in range(n)]

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