from
  $blog10 = int($mindigits / 2)
to
  my $low = $mindigits - 1;
  my $high = int($maxdigits / 2);
  my $blog10 = $low <= $high ? $low : $high;

##</code><code>##

Sample id 29, 38863124 ... 04402533 (2503 digits)
  With carry_lim at 50, result 38863124 ... 04402533 (2503 digits) is Succeeded.
  With carry_lim at 75, result 38863124 ... 04402533 (2503 digits) is Failed.