|   |   |   |   |   X   |   |   
|   |   |   |   X   |   |   |   
X---@---+---+---@   |   |   |   
|   X---@---+---+---@   |   |   
|   |   X---@---+---+---@   |   
|   |   |   X---+---+---+---@   
|   |   X---@---+---+---@   |   
|   X---@---+---+---@   |   |   
X---@---+---+---@   |   |   |   
|   X---@---+---+---@   |   |   
|   |   X---@---+---+---@   |   
|   |   |   X---+---+---+---@   
|   |   X---@---+---+---@   |   
|   X---@---+---+---@   |   |   
|   |   |   |   |   X   |   |   
|   |   |   |   X   |   |   |   
