#!/usr/bin/env perl
use strict;
use warnings;
use Encode;
die "gimme args" unless @ARGV;
$^I = ".unmangled.by.$$";
while (<>) {
    s/&#(\d+);/chr($1)/ge;
    $_ = decode_utf8($_, 1);
    s/(\P{ASCII})/ "&#" . ord($1) . ";" /ge;
    print;
}