or download this
#!/usr/bin/perl -w
use strict;$|++;$_=<DATA>;y,a-zA-Z,a-hA-N i-qO-Zr-z,,my @i=split//;pri
+nt chr(10).chr(13);my @o=("A");my $c=65;select(undef,undef,undef,0.01
+),$o[$#o+1]=chr(++$c),print chr(8).$o[$#o-1].chr(8)for(0..$#i);print
+chr(10).chr(13);for my$c(0..$#i){my($e,$d)=(0,$c);select(undef,undef,
+undef,$e),$e=($#o/($#o-$c+1))*0.010,$o[$d]=($c/++$d%2)?chr(ord($o[$d+
+1])):$o[$d],print chr(8).$o[$d].chr(8)for($c..$#i);print$i[$c].chr(10
+);}__DATA__
!rVTUwiCDUheSwHeSAwpaczeS!
or download this
#!/usr/bin/perl -w
use strict;$|++;$_=<DATA>,y,0-9A-Za-z,G-PzA-B{($_)}="@ ;3r-yC-F81a-q,;
+sub _{chr(8)x shift};sub _1{print@_};my@i=split//;my($u,@o)=(undef
,("A"));select($u,$u,$u,0.01),$o[$#o+1]=chr(66+$#o),_1 $o[$#o-1]for(0.
+.$#i);_1 _$#o+1;for my$c(0..$#i){my($e,$d)=(0,$c);$e=($#o/($#o-$c+
1))*0.010,select($u,$u,$u,$e),$o[$d]=($c/++$d%2)?$o[$d+1]:$o[$d],_1 $o
+[$d]for($c..$#i);_1 _(1),$i[$c],_ $#o+1 }_1 "\n"__DATA__
!Phnfd1MoPh9MPhkRrqBMRQS3!