1 - Cube It
	A ‘T’ shaped piece of cardboard of appropriate dimensions can be folded into a cube with no gaps and no overlaps.  Of course one might need some duct tape to hold the cube together.  With a bit of thought, one will discover that certain variations to that ‘T’ shape are also useable for cube making.  Your task is to examine various rectilinear simple polygonal shapes of  flat cardboard with integer dimensions and determine which ones can be folded (the folds also being rectilinear) into cubes with no overlaps or gaps.  (hint:  A bit of analysis will reveal that a rectilinear simple polygon has 4 more outside corners than inside corners, and at least 2 of the inside corners will be corners of any resulting cube.)
Input:
There will be multiple cases.  Each line of input represents one of the cases except that the last line will contain a single 0.  The number of square corners (at most 20) in the cardboard sheet is listed first.  This is followed by the x and y coordinates (integers) of the corners listed in clockwise sequence.
Output:
For each case you should determine whether or not the cardboard can be folded into a cube.  If it can, display the length of a side.  If it can not, display the message “sorry”.  Number each case as shown in the example.  Spacing is not important.
Sample Input:
12    0  0    0  2   -1  2   -1  3   0  3   0  4   1  4   1  3   2  3   2  2   1  2   1  0
4     1  1     1  7    7  7    7  1
0
Sample Output:
1.  1
2.  sorry