N = int(input())
P = 10 ** 9 + 7
dp = [[0] * 3 for _ in range(N)]
dp[0][0] = 1

for i in range(1,N):
    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]) % P
print(sum(dp[N-1]) % P)