# No.314 ケンケンパ
def main():
    N = int(input())
    MOD = 10 ** 9 + 7
    a, b, c = 0, 1, 0  # パー, ケン, ケンケン
    for i in range(N - 1):
        a, b, c = (b + c) % MOD, a, b
    print((a + b + c) % MOD)


if __name__ == "__main__":
    main()