20
..........x....xxo..
.........o......x...
............o...ox.x
..ooox..............
..oo......o..x....o.
..ox....x...........
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...o.....x......x...
..x..........o.x..o.
...x......o....o.x..
....xo...o.......o..
x....x.............x
.x.o........x..x..oo
..................oo
...x..o.......o.o.o.
oo.......o.x....x.xx
.x..x..x.........x..
.xx..o............o.
.x........o.xo.....o
x................x.o
