#!/usr/bin/perl -w

use strict;

# shift(@ARGV);
my %found_in;
while (<>) {
#  $found_in{$_} .= $ARGV;
   $found_in{$_}{$ARGV}++;
}
print "file1 and not file2:\n";
print grep { $found_in{$_} eq "file1" } keys %found_in;
print "file2 and not file1:\n";
print grep { $found_in{$_} eq "file2" } keys %found_in;

exit;