my $sortstr = join('', @list);
my @sorted_list = sort {
    my ($tmp1,$tmp2);
 (($tmp1 = index($sortstr,substr($a,0,1))) >= 0 ? $tmp1 : length($sortstr))
    <=> 
 (($tmp2 = index($sortstr,substr($b,0,1))) >= 0 ? $tmp2 : length($sortstr))
        ||
        $a cmp $b
    } @list2;