20
......ox..o.xx......
..x....x...o....o...
.o.........x....x...
................x...
.o.......x....o.....
...x........o...o...
x....x..............
...........x.xxox...
........xx..........
..o.........o...o..o
x..o.....xx.........
x..x..xx............
o..o.x...o...o...o.x
.xx..xx..o.x........
..o.o......o..o.....
o.........o.......o.
x..xx..x.o..o.......
.o......x.....o....x
..........oo...o..o.
..xo.......xo...o..o
