Mr. Koch wandered into the kitchen after a doughnut, and saw black and
white squares all over the floor. “Aha,” thought he, “like a flash, an
idea!” This is it.
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|#####| 1 | | 2 | 3 | 4 | 5 |#####| 6 | | 7 | 8 | 9 | 10 |#####|
|#####| | | | | | |#####| | | | | | |#####|
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 11 | |#####| 12 | | | | 13 | |#####| 14 | | | | 15 |
| | |#####| | | | | | |#####| | | | | |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 16 | | 17 | |#####| 18 | | | | 19 | |#####| 20 | | |
| | | | |#####| | | | | | |#####| | | |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 21 | | | | 22 | |#####| 23 | | | | 24 | |#####| |
| | | | | | |#####| | | | | | |#####| |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| |#####| 25 | | | | 26 | |#####| 27 | | | | 28 | |
| |#####| | | | | | |#####| | | | | | |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 29 | 30 | |#####| 31 | | | | 32 | |#####| 33 | | | |
| | | |#####| | | | | | |#####| | | | |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 34 | | | 35 | |#####| 36 | | | | 37 | |#####| 38 | |
| | | | | |#####| | | | | | |#####| | |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|#####| 39 | | | | 40 | |#####| 41 | | | | 42 | |#####|
|#####| | | | | | |#####| | | | | | |#####|
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 43 | |#####| 44 | | | | 45 | |#####| 46 | | | | 47 |
| | |#####| | | | | | |#####| | | | | |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 48 | | 49 | |#####| 50 | | | | 51 | |#####| 52 | | |
| | | | |#####| | | | | | |#####| | | |
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| 53 | | | | 54 | |#####| 55 | | | | 56 | |#####| |
| | | | | | |#####| | | | | | |#####| |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| |#####| 57 | | | | 58 | |#####| 59 | | | | 60 | |
| |#####| | | | | | |#####| | | | | | |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 61 | 62 | |#####| 63 | | | | 64 | |#####| 65 | | | |
| | | |#####| | | | | | |#####| | | | |
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| 66 | | | 67 | |#####| 68 | | | | 69 | |#####| 70 | |
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+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|#####| 71 | | | | | |#####| 72 | | | | | |#####|
|#####| | | | | | |#####| | | | | | |#####|
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