sub inc {
  my $str = uc shift;

  $str =~ s/XLVIII$/IL/      or
  $str =~ s/VIII$/IX/        or
  $str =~ s/III$/IV/         or
  $str =~ s/DCCCXCIX$/CM/    or
  $str =~ s/CCCXCIX$/CD/     or
  $str =~ s/LXXXIX$/XC/      or
  $str =~ s/XXXIX$/XL/       or
  $str =~ s/(I{1,2})$/$1I/   or
  $str =~ s/CDXCIX$/D/       or
  $str =~ s/CMXCIX$/M/       or
  $str =~ s/XCIX$/C/         or
  $str =~ s/I([VXLCDM])$/$1/ or
  $str =~ s/([VXLCDM])$/$1I/;

  return $str;
}

sub dec {
  my $str = uc shift;

  $str =~ s/IL$/XLVIII/      or
  $str =~ s/IX$/VIII/        or
  $str =~ s/IV$/III/         or
  $str =~ s/CM$/DCCCXCIX/    or
  $str =~ s/CD$/CCCXCIX/     or
  $str =~ s/XC$/LXXXIX/      or
  $str =~ s/XL$/XXXIX/       or
  $str =~ s/III$/II/         or
  $str =~ s/II$/I/           or
  $str =~ s/([VXLCDM])I$/$1/ or
  $str =~ s/([VXL])$/I$1/    or
  $str =~ s/D$/CDXCIX/       or
  $str =~ s/M$/CMXCIX/       or
  $str =~ s/C$/XCIX/;

  return $str;
}
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