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                                      EXHIBIT B

                                JOINT FILING AGREEMENT


          The undersigned acknowledge and agree that the foregoing statement on
Schedule 13G is filed on behalf of each of the undersigned and that all
subsequent amendments to this statement on Schedule 13G shall be filed on behalf
of each of the undersigned without the necessity of filing additional joint
acquisition statements.  The undersigned acknowledge that each shall be
responsible for the timely filing of such amendments, and for the completeness
and accuracy of the information concerning him or it contained therein, but
shall not be responsible for the completeness and accuracy of the information
concerning the other, except to the extent that he or it knows or has reason to
believe that such information is accurate.


Dated: February 12, 1998


                                             The TCW Group, Inc.

                                             
                                             By:  /s/ Mohan V. Phansalkar
                                                  ----------------------------
                                                  Mohan V. Phansalkar
                                                  Authorized Signatory     
                                   


                                             Robert Day

                                                  
                                             By:  /s/ Mohan V. Phansalkar
                                                  ----------------------------
                                                  Mohan V. Phansalkar
                                                  Under Power of Attorney dated
                                                  January 30, 1996, on File with
                                                  Schedule 13G Amendment Number
                                                  1 for Matrix Service Co. dated
                                                  January 30, 1996.







                                         B-1
