How to divide points into two groups?

Question

Pascal

Hello! Need help.
I am given 4 points A, B, C, D and a line GK.
GK can lie anywhere (Not necessarily parallel to one of the axes).
Points A, B, C, D can be entered in any order. Those. maybe A, B on one side of GK, and C, D on the other, or maybe A, C on one side, and B, D on the other.
It is necessary to divide the points into two groups. The first group on one side is GK, the second group on the other side is GK.
How to split points into two groups? The coordinates of all points are known (A,B,C,D,G,K).