CUSIP No. 67612W108 AGREEMENT CONCERNING JOINT FILING OF AMENDMENT NO. 4 TO SCHEDULE 13D The undersigned agree as follows: (i) each of them is individually eligible to use Schedule 13D to which this Exhibit is attached, and such Schedule 13D is filed...

CUSIP No.  00000X000

                        AGREEMENT CONCERNING JOINT FILING
                       OF AMENDMENT NO. 4 TO SCHEDULE 13D

         The undersigned agree as follows:

         (i) each of them is individually eligible to use Schedule 13D to which
this Exhibit is attached, and such Schedule 13D is filed on behalf of each of
them; and

         (ii) each of them is responsible for the timely filing of such Schedule
13D and any amendments thereto, and for the completeness and accuracy of the
information concerning such person contained therein; but none of them is
responsible for the completeness or accuracy of the information concerning the
other person making the filing, unless such person knows or has reason to
believe that such information is inaccurate.

         This Agreement may be executed in any number of counterparts, each of
which shall be deemed to be an original, but all of which, taken together, shall
constitute one and the same instrument.

         Dated: December 27, 2005

                                         V. XXXX XXXXX

                                         /s/  V. Xxxx Xxxxx
                                        ----------------------------------------

                                         1109519 ONTARIO LIMITED

                                      By:  /s/  V. Xxxx Xxxxx
                                         ---------------------------------------
                                         Name:   V. Xxxx Xxxxx
                                         Title:  President


                                         THE SIXTY TWO INVESTMENT
                                         COMPANY LIMITED

                                      By: /s/  V. Xxxx Xxxxx
                                         ---------------------------------------
                                         Name:   V. Xxxx Xxxxx
                                         Title:  President


                                         810679 ONTARIO LIMITED

                                      By:  /s/  V. Xxxx Xxxxx
                                          --------------------------------------
                                          Name:   V. Xxxx Xxxxx
                                          Title:  President


                                          FAIRFAX FINANCIAL HOLDINGS LIMITED

                                       By: /s/  Xxxx X. Xxxxxxxx
                                          --------------------------------------
                                          Name:   Xxxx X. Xxxxxxxx
                                          Title:  Vice President,
                                          Corporate Affairs

                                          FFHL GROUP LTD.

                                       By:  /s/  Xxxx X. Xxxxxxxx
                                          --------------------------------------
                                          Name:   Xxxx X. Xxxxxxxx
                                          Title:  Vice President


                                          FAIRFAX INC.

                                       By:  /s/  Xxxx X. Xxxxxxxx
                                          --------------------------------------
                                          Name:   Xxxx X. Xxxxxxxx
                                          Title:  Vice President



                                         FAIRFAX FINANCIAL (US) LLC.

                                      By:  /s/  Xxxxxxx X. Xxxxxx
                                         ---------------------------------------
                                         Name:   Xxxxxxx X. Xxxxxx
                                         Title:  Vice President


                                         TIG HOLDINGS, INC.

                                      By: /s/  Xxxxxxx X. Xxxxx
                                         ---------------------------------------
                                         Name:  Xxxxxxx X. Xxxxx
                                         Title: Senior Vice
                                                President, Chief Financial
                                                Officer and Treasurer

                                         TIG INSURANCE GROUP, INC.

                                      By: /s/  Xxxxxxx X. Xxxxx
                                         ---------------------------------------
                                         Name:  Xxxxxxx X. Xxxxx
                                         Title: Senior Vice President, Chief
                                                Financial Officer and Treasurer


                                         TIG INSURANCE COMPANY

                                      By: /s/  Xxxxxxx X. Xxxxx
                                         ---------------------------------------
                                         Name:   Xxxxxxx X. Xxxxx
                                         Title:  Senior Vice President, Chief
                                                 Financial Officer and Treasurer


                                         ORH HOLDINGS INC.

                                      By:  /s/  Xxxx X. Xxxxxxxx
                                         ---------------------------------------
                                         Name:   Xxxx X. Xxxxxxxx
                                         Title:  Vice President


                                         UNITED STATES FIRE INSURANCE COMPANY

                                      By:  /s/  Xxxxx Xxx Xxxx
                                         ---------------------------------------
                                         Name:   Xxxxx Xxx Xxxx
                                         Title:  Vice President