I think the obstacles we encounter virtual rock pile. Depending on what we are used to build a bridge to cross the river. Or building a wall to themselves
I think a virtual stack rocks and obstacles-we come across. Depending on whether we will build a bridge to cross the river or building walls in order to hedge themselves
I think that virtual obstacle of the rock pile, we met up with that we will be creating a bridge to walk across the river to build the wall to block or the self-