use bytes;
    if (vec($s,3,2) < 3) {
        () = $s =~ m/.(?=.)(?{ vec($s,pos($s)-1,8) = vec($s,pos($s),8)})/sg;
        chop($s);
    }
    else {
        () = $s =~ m/.(?=.)(?{ vec($s,pos($s)-1,8) = vec($s,pos($s),8)})/sg;
        chop($s);
        while (vec($s,3,2) == 2) {
            () = $s =~ m/.(?=.)(?{ vec($s,pos($s)-1,8) = vec($s,pos($s),8)})/sg;
            chop($s);
        }
    }