Fill the Square
---------------

In this problem, you have to draw a square using uppercase English alphabets.

To be more precise, you will be given a square grid with some empty blocks and 
others already filled for you with some letters to make your task easier.  You 
have to insert characters in every empty cell so that the whole grid is filled 
with alphabets.  In doing so you have to meet the following rules:

- Make sure no adjacent cells contain the same letter; two cells are adjacent 
  if they share a common edge.   
- There could be many ways to fill the grid.  You have to ensure you make the 
  lexicographically smallest one. Here, two grids are checked in row major order 
  when comparing lexicographically. 
 
Input
-----
The first line of input will contain an integer that will determine the number 
of test cases.  Each case starts with an integer n (n <= 10), that represents 
the dimension of the grid.  The next n lines will contain n characters each. 
Every cell of the grid is either a '.' or a letter from [A, Z]. Here a '.' 
represents an empty cell.

Output
------
For each case, first output Case #: (# replaced by case number) and in the next 
n lines output the input matrix with the empty cells filled heeding the rules above.
 
Sample Input
------------
2
3
...
...
...
3
...
A..
...

Sample output
-------------
Case 1:
ABA
BAB
ABA
Case 2:
BAB
ABA
BAB