Bug in the code

[Athulpai12]

The code for ABBA div1 is incorrect it does not work for the input
A
BAAA
The answer should be possible but the code produces impossible

[saurabh-sp-tripathi]

Same for example BBABAAAAAA ... it says impossible instead of impossible but interestingly 'Topcoder' accepts this as answer.

What I can make out of this is, on topcoder you don't necessarily have to put the right answer, sometimes you can be just lucky enough to pass there test sample.