X                  X
X DDDD        DDDD X
X DDDD        DDDD X
X  DDDD      DDDD  X
X D DDDD    DDDD D X
X DD DDDD  DDDD DD X
X DD DDDD  DDDD DD X
X D DDDD    DDDD D X
X  DDDD      DDDD  X
X DDDD        DDDD X
X DDDD        DDDD X
X  DDDD      DDDD  X
X D DDDD    DDDD D X
X DD DDDD  DDDD DD X
X DD DDDD  DDDD DD X
X D DDDD    DDDD D X
X  DDDD      DDDD  X
X DDDD        DDDD X
X DDDD        DDDD X
X                  X