Evaluate the given limit:
$$ \lim_{n \to \infty} \bigg[ \bigg(\frac{n}{n} \bigg)^n +\bigg(\frac{n-1}{n} \bigg)^n + \bigg(\frac{n-2}{n} \bigg)^n+....+\bigg(\frac{1}{n} \bigg)^n \bigg]$$
I was trying to calculate each limit separately. First bracket equals $1$, second bracket equals $1/e$ , third bracket equals $1/e^2$ and so on. But how to add up after that? Could someone help me with this?