+     +-----+-----+-----+-----+-----+     +
            "     "     |     "           |
            "  8  "  7  |  6  "           |
            "     "     |     "           |
+=====+=====+-----+=====+-----+=====+=====+
|     |     |     "     "     |     |     |
|  6  |  3  |  5  "     "  8  |  1  |  2  |
|     |     |     "     "     |     |     |
+-----+-----+-----+=====+-----+-----+=====+
|     |     |     |     "     |     "     |
|  4  |  1  |  2  |  7  "  4  |  5  "  7  |
|     |     |     |     "     |     "     |
+=====+=====+=====+=====+-----+=====+-----+
|     |     |     "     "     "     |     |
|  7  |  2  |  1  "     "  3  "  3  |  6  |
|     |     |     "     "     "     |     |
+-----+-----+=====+     +=====+-----+-----+
|     |     "     "     "     |     |     |
|  5  |  8  "  4  "     "  1  |  5  |  2  |
|     |     "     "     "     |     |     |
+-----+-----+-----+=====+=====+-----+-----+
|     |     "     |     |     "     |     |
|  6  |  3  "  2  |  7  |  3  "  8  |  4  |
|     |     "     |     |     "     |     |
+=====+-----+-----+-----+-----+=====+=====+
      "     "     |     |     |     "     |
      "  4  "  5  |  1  |  6  |  8  "     |
      "     "     |     |     |     "     |
+-----+-----+-----+-----+-----+-----+-----+