8
7
5
1
white
  O |=~
+---+  
||_|   
 / \   
<   v  
  O    
+---+__
||_|  |
  |\  $
  L<   
  O |=~
+---+  
||_|   
  |\   
  L v  
  O    
+---+__
||_|  |
 / \  $
<   v  
  O |=~
+"""+  
|[_]   
 > |   
<  L   
  O    
+"""+__
|[_]  |
  >|  $
 < L   
  O |=~
+"""+  
|[_]   
  |\   
  L<   
  O    
+"""+__
|[_]  |
  |\  $
  L v  