.............. 
  .............  
   ...........   
    #........    
     #......     
      #...Z#     
∆     #....#     
 ∆    #....#    ∆
 ∆    #....#     
∆∆    #....#    ∆
∆∆∆   #....#   ∆ 
∆∆∆   #r...#   ∆∆
 ∆∆   #bM..#   ∆∆
 ∆    #.M∩.#    ∆
      ######