17 27
FFFFFFFFFFFFFFFFFFFFFFFFFFF
  F F     F     F     F   F
F F FFF F F F FFF    FF FFF
F F F   F F F     F   F   F
F F FFFFF F FFF FFF FFF F F
F         F F F   F     F F
FFFFFFF FFFFF F   FFF F F F
F F F F F   F         F F F
F F F FFF FFFFF FFFFF FFFFF
F F F F F   F F F F       F
F F F F FFFFF FFF FFF FFFFF
F F   F     F             F
FFFFF FFF FFF FFFFF FFF FFF
F       F F     F F F     F
F FFF FFF F F FFF FFFFF FFF
F   F   F   F       F      
FFFFFFFFFFFFFFFFFFFFFFFFFFF