An island with two trees. From one of the black dots you can see two trees, but from the other you can only see 1, since the other is hidden behind it. (For the purposes of this puzzle the island is empty apart from the trees, and a tree is hidden only when it lies directly behind another tree from the perspective of the observer).

**Problem 1**

*The island has 5 trees positioned at the vertices of a regular pentagon, as below. Is it possible for you and two friends to stand on the island, so that the three of you can each see a different number of trees? *