mod = (10 ** 9 + 7)


def main():
    n = int(input())

    zero, one, one_one = 0, 1, 0
    for _ in range(1, n):
        zero, one, one_one = one + one_one % mod, zero % mod, one % mod

    print((zero + one + one_one) % mod)

if __name__ == '__main__':
    main()