Exhibit B - Opinion Letter of CIBC World Markets Corp.

December 28, 1999



Board of Directors
CNY Financial Corporation
1 North Main Street
Cortland, NY 13045

Directors:

         You have  requested  our opinion as to the  fairness,  from a financial
point of view, to the holders of the  outstanding  shares of common stock of CNY
Financial  Corporation  (the "Company") of the  consideration  to be received by
such  shareholders  from  Niagara  Bancorp,  Inc.  ("Niagara")  pursuant  to the
definitive  Agreement  and Plan of Merger to be dated as of December 28, 1999 by
and  between  Niagara  and  the  Company  (the  "Agreement").  Pursuant  to  the
Agreement,  the Company will be merged with and into Niagara, the Company's sole
bank  subsidiary  will  become a wholly  owned  subsidiary  of Niagara  and each
outstanding share of the Company's common stock will be converted into the right
to receive $18.65 - $18.75 in cash (the "Consideration").

         In connection  with this opinion we have reviewed,  among other things:
(a) the Agreement;  (b) the Stockholders  Agreements and Seller Option Agreement
(as such terms are defined in the Agreement); (c) audited consolidated financial
statements and management's  discussions and analysis of the financial condition
and results of  operations  for the Company and for Niagara for the three fiscal
years ended December 31, 1998; (d) unaudited  consolidated  financial statements
for the Company and for Niagara for the nine months  ended  September  30, 1999;
(e) certain other publicly available business and financial information relating
to the Company and to Niagara; (f) the views of senior management of the Company
of  the  past  and  current  business  operations,  results  thereof,  financial
condition  and future  prospects  of the Company;  (g) a  comparison  of certain
financial information for the Company with similar information for certain other
companies we considered  comparable to the Company;  (h) the financial  terms of
certain recent business  combinations in the banking  industry;  (i) the current
market environment generally and the banking environment in particular;  and (j)
such other  information,  financial  studies,  analyses and  investigations  and
financial,  economic and market  criteria as we  considered  appropriate  in the
circumstances.

                                      B-1



         We have relied, without independent  verification or investigation,  on
all of the financial information, analyses and other information furnished to us
for  purposes  of this  opinion,  including  information  relating to assets and
liabilities,  contingent or otherwise,  as being complete and accurate.  We have
also relied upon the  management  of the  Company as to the  reasonableness  and
achievability of the financial and operating forecasts and projections  provided
to us. In that regard, we have assumed,  with your consent, that such forecasts,
projections  and estimates  have been  reasonably  prepared and reflect the best
currently  available estimates and judgments of the management of the Company as
to the  future  financial  performance  of the  Company.  We  have  not  made an
independent evaluation or appraisal of the assets and liabilities of the Company
or any of its  subsidiaries  and we  have  not  been  furnished  with  any  such
evaluation or appraisal. Furthermore, this opinion shall not constitute any such
evaluation or appraisal.  We were not asked to, and did not, solicit indications
of interest from any other person regarding a business combination involving the
Company.

         We have acted as financial  advisor to the Company in  connection  with
the  Merger  and will  receive a fee for our  services,  a  portion  of which is
contingent  on the  consummation  of the Merger.  In the ordinary  course of our
business,  we may  actively  trade the equity  services  of the  Company  and of
Niagara for our own account and for the accounts of customers,  and  accordingly
may at any time  hold a long or short  position  in such  securities.  In April,
1998,  we acted as lead  advisor in  Niagara's  mutual to stock  conversion.  We
currently provide equity research coverage of Niagara and make a market in their
stock.


         It is understood  that this opinion is for the information of the Board
of Directors in  connection  with its  consideration  of the Merger and does not
constitute a recommendation to any stockholder as to how such stockholder should
vote on the merger.


         Based  upon and  subject  to the  foregoing  and based  upon such other
matters as we consider relevant,  it is our opinion that, as of the date hereof,
the  Consideration  to be received by the common  shareholders of the Company in
the Merger is fair, from a financial point of view, to such shareholders.

                                        Very truly yours,



                                        /s/ CIBC WORLD MARKETS
                                        ---------------------------------
                                            CIBC World Markets