@grid[$dim / 2 - 1][$dim / 2 ] = 1; @grid[$dim / 2 - 1][$dim / 2 + 1] = 1; @grid[$dim / 2 ][$dim / 2 ] = 1; @grid[$dim / 2 ][$dim / 2 - 1] = 1; @grid[$dim / 2 + 1][$dim / 2 ] = 1; @.grid := @grid;