Which of the sequences $\left\{a_{n}\right\}$ converge, and
which diverge? Find the limit of each convergent sequence.
$$
a_{n}=\left(1-\frac{1}{2}\right)+\left(\frac{1}{2}-\frac{1}{3}\right)+\left(\frac{1}{3}-\frac{1}{4}\right)+\cdots \\ \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad +\left(\frac{1}{n-2}-\frac{1}{n-1}\right)+\left(\frac{1}{n-1}-\frac{1}{n}\right)
$$