7 matchsticks are arranged into the stylized image of a dog. The dog is watching to the right.
It is enough to move 3 matchsticks to a new position in order to make the dog watching in another direction. The image of the dog can be rotated, but it has to remain identical with the initial one.
There are two solutions to this puzzle. Which matchstick is never moved with any of the solutions?
Two possible solutions are shown in the diagram. In either of them the “backbone” matchstick is never moved.