.
                                 B
                            o  o x   o
                         x     B o     x
                       B       x B        B
                      o        o  x          o
                     x            B             x
                    B             o               B
                   o               x                o
                  x                B                 x
                  B               o                  B
                   o             x   B               o
                   x            o      x             x
                    B          B       o            B
                       o        x      B           o
                         x       o     x        x
                             B       B       B
                                       o
                                       x