Determine whether the sequences are increasing, decreasing, or not monotonic. If increasing, enter 1 as your answer. If decreasing, enter $-1$ as your answer. If not monotonic, enter 0 as your answer.

1. $\displaystyle a_n = \frac{\cos n}{2^n}$
2. $\displaystyle a_n = \frac{\sqrt{n + 2}}{8 n + 2}$
3. $\displaystyle a_n = \frac{1}{2 n + 8}$
4. $\displaystyle a_n = \frac{n - 2}{n + 2}$