Here’s a story.
A lady prepared a game to introduce the software to one of her clients. They were sitting around the table to understand the concept of the game. The client loved the game so much that instead of just checking out how the first points worked they went on to play the whole game all the way to the finish using the fast forward option that we have built in.
However at some stage it appeared that it is not possible to reach the finish. Here is the strategy they used. Starting from 2 can you find the way to finish (21)?