+===I===I===I===I=======I=======+
| |:::| |:::| ::::| ::::|
I===I...I===I...I...+===I...+===I
|:::| ::::: |:::| ::::: |
|...|...+===I...I...+===+...+===I
| |:::| |:::| ::::| ::::|
|...+===+...+===I===I===I=======I
|:::: ::::: |:::| ::::: |
I===========I===I...I===I===+...|
| ::::: |:::| |:::| |:::|
|...+===+...|...|...|...I===+...|
|:::| |:::| |:::| |:::: |
|...|...|...|...I===+...+===+...|
| |:::| |:::| ::::: |:::|
I===+...+===I...+=======I===+...|
|:::: ::::| ::::: |:::: |
+===========I===================+
The pieces may be fitted together, as shown in the illustration, to form
a perfect chessboard.