This kind of problem is new to me, and I am having a hard time to approach it it. Can someone help please?

1) Evaluate the integrals $\displaystyle \int_\gamma z^n dz$ for all integers n, where $\displaystyle \gamma$ is any circle centered at the origin with counterclockwise orientation.

2) Same question but with $\displaystyle \gamma$ being any circle not containing the origin.