#!/usr/bin/perl -l

# http://perlmonks.org/?node_id=1178025

use strict;
use warnings;
use Algorithm::Diff qw(traverse_sequences);

while(<DATA>)
  {
  my ($want, $in) = split;
  my @from = split //, $in;
  my @to = split //, $want;
  my $answer = '';

  traverse_sequences( \@from, \@to,
    {
    MATCH     => sub {$answer .= $from[shift()]},
    DISCARD_A => sub {$answer .= "-$from[shift()]"},
    DISCARD_B => sub {$answer .= "+$to[pop()]"},
    } );
  $answer =~ s/^(?:[+-]\w)+ | (?:[+-]\w)+$//gx; # strip outer
  $answer =~ tr/+-//d; # clean up inner
  $answer ||= 'not found';
  print "$want in $in is $answer";
  }

__DATA__
ABC DFGABCKBG
ABC DFGAXBHCY
ABC DFGAXBHY
ABC DEFGHI