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)