perl -MAlgorithm::Line::Bresenham=line -le'($A,$B)=@ARGV;@p=map{$_->[0]}line($A,1,1,$B);$l=$p[1];for(1..$B){if($p[$_]==$l){push@a,"A"}else{push@a,"B";$l=$p[$_]}}print$_ for@a' 10 40