This is an one-liner. As you can see, you can check the threshold value for items to show up by tuning the constant. Hope this helps.

map { print $_ if ( $h{$_}++ == 1) } <DATA>;

__DATA__
A(01) 
A(01) 
A(01) 
B(02) 
C(03) 
A(01) 
D(04) 
E(05) 
...
[download]

One-liners are definitely funny.