foreach $unicode (keys %from) {
    if (defined($to{$unicode})) {
        if ($from{$unicode} ne $to{$unicode}) {

            my $fromhex = $from{$unicode};
            my $tohex = $to{$unicode};

            $wrong = $wrong . '\\' . 
                        sprintf('%o', hex $fromhex);
            $right = $right . '\\' . 
                        sprintf('%o', hex $tohex);

        }

    }
}