What do I do if I have more than one maxes or mins?

For example in this problem.

Let $\displaystyle f(x)=-x^2+3x$ on the interval $\displaystyle [1,3]$. Find the Absolute Maximum and absolute minimum of f(x) on this interval.

I know that the min occurs at x=3.

But I don't understand what to put if I have more than one (in this case) max.