#! /opt/third-party/bin/perl

open(FILE, "<", "a" ) || die "Unable to open file a <$!>\n";

while ( <FILE> ) {
  chomp;
  $fileHash{$_} = $i++;
}

close(FILE);

open(FILE, "<", "b" ) || die "Unable to open file a <$!>\n";

while( <FILE> ) {
  chomp;
  if( exists $fileHash{$_} ) {
  }
  else {
    print "$_\n";
  }
}

close(FILE);

exit 0