Case #1: 
.......
R......
RB.....
BRBR...
RBB....
.......
.......
Case #2: 
R.....
BRRR..
......
BR....
BBB...
BRBR..
Case #3: 
BBBR
RRR.
....
....
Case #4: 
RRB
BB.
...