#!/usr/bin/perl

open(FILE, "<", "a1.txt" ) || die "Unable to open file a <$!>\n";
while ( <FILE> ) {
        chomp;
        $fileHash{$_} = $i++;
}
close(FILE);
open(FILE, "<", "a2.txt" ) || die "Unable to open file a <$!>\n";
while( <FILE> ) {
        chomp;
        if( exists $fileHash{$_} ) {
          }
        else {
                print "$_\n";
        }
}
close(FILE);
exit 0