if($str !~ /[IVXLCDM]+/         ||
                 $str =~ /([IXC])\1{3,}/      ||
                 $str =~ /([VLD])\1{1,}/  ||

                 $str =~ /I[VXLCDM][IVXLCDM]/ ||
                 $str =~ /V[XLCDM][VXLCDM]/   ||
                 $str =~ /L[CDM][LCDM]/       ||
                 $str =~ /X[LCDM][XLCDM]/     ||
                 $str =~ /C[DM][CDM]/         ||
                 $str =~ /DM[DM]/) {
                  return 0;
              }

              return 1;