What is the nature of the surface at the point of partial derivative equality?

[KingBigness]

Homework Statement

Let f(x,y)=1−x^{2}−y^{2}. Find the point at which

\frac{\partial f}{\partial x} = \frac{\partial f}{\partial y} = 0
and illustrate graphically the nature of the surface z = f (x, y) at this point.

The Attempt at a Solution

Just did the partial derivatives and got 2x=2y=0 hence x=0 and y=0

So illustrating z=f(x,y) at this point give z=1

Creating a contour plot I get the plot attached below.

This question is part of a difficult assignment I got from uni but this question seems way to easy in comparison to the rest of the assignment. I just want to make sure there isn't something I missed or is it really this simple?

Thank you

 

[KingBigness]

Any help?