sub enq{
	my($y,$x)=@_;
	if($y>0&$y<=$n&$x>0&$x<=$n&&!$$y[$x]++){
		print"$y $x\n";
		push@s,[$y,$x]if<>=~B;
	}
}
$|=1;
$n+=<>;
enq(1,1);
while($_=pop@s){
	($y,$x)=@$_;
	enq($y+1,$x);
	enq($y,$x+1);
	enq($y,$x-1);
	enq($y-1,$x);
}
print$$n[$n]?Yes:No,$/;