20
......xx.......x....
x..........x........
.o..x..............o
..o.o......x........
o......o.o....o.....
......x.............
x..x.......o.x..x...
.........o..........
....x...x....o.ox.o.
o........xoox.o...o.
.o..........x...x.o.
..x.o.x.....x..xx...
x..ox....xo.x..oo...
.............x......
....x......o.x.oo...
............o.......
...x......xo.....o.x
.oo.x........xoo....
x....o..o.ooox......
..x...x.............
