for(1..<>){
	<>;
	$_=<>;
	s/^BB/AB/ ||
	s/^B?A\KAB*/$&=~y,AB,BA,r/e ||
	s/^B?ABA*\KB*/$&=~y,B,A,r/e ||
	s/AA/AB/;
	s/A+/$&=~y,A,B,r/e;
	print;
}