mod = 10**9+7
N = int(input())
DP = [[0] * 3 for _ in range(N+1)]
DP[0][0] = 1
for i in range(N):
    DP[i+1][0] = (DP[i][1] + DP[i][2]) % mod
    DP[i+1][1] = DP[i][0]
    DP[i+1][2] = DP[i][1]
print((DP[N][0] + DP[N][1] + DP[N][2]) % mod)