Markers can move forward one square, or can jump over a marker of either colour if there is an empty square to land on.
Markers are not removed from the board if jumped.
You DO NOT have to alternate moving black and white markers.
The x's move E or S and o's move N or W and the goal is to make the x's and o's change places in these two board positions and in the general case.

Easy:

+-+-+-+    N
|x|x|x|  W + E
+-+-+-+    S
|x| |o|
+-+-+-+
|o|o|o|
+-+-+-+


Medium:

+-+-+-+-+-+
|x|x|x|x|x|
+-+-+-+-+-+
|x|x|x|x|x|
+-+-+-+-+-+
|x|x| |o|o|
+-+-+-+-+-+
|o|o|o|o|o|
+-+-+-+-+-+
|o|o|o|o|o|
+-+-+-+-+-+