#!/usr/local/bin/perl -w
use strict;
use warnings;
use utf8;

utf8::decode(my $text0 = "\x{3042}"  ); # clean
utf8::decode(my $arg   = $ARGV[0]    ); # tainted
utf8::decode(my $text1 = "$arg$text0"); # tainted
utf8::decode(my $text2 = "$text0$arg"); # tainted

print length($text1), "\n";
print length($text2), "\n";