+-----------------------------+ | | | | | +-------------------+-------------------+ | | v v +---+ +---+ +---+ +---+ +---+ +---+ +---+ +----+ +----+ | 4 | <-- | | --> | 2 | --> | 5 | --> | 6 | --> | 7 | --> | 8 | --> | 10 | --> | 11 | +---+ | | +---+ +---+ +---+ +---+ +---+ +----+ +----+ | | ^ ^ | ^ | 1 | ------+ | | | | | | v | | | | +---+ | | | | | 9 | -----------------+ +---+ | +---+ | | | | v | +---+ | | 3 | ----------------+ +---+