EXHIBIT 2

CUSIP No. 195293105

AGREEMENT CONCERNING JOINT FILING

OF SCHEDULE 13G

The undersigned agree as follows:

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

(ii) each of them is responsible for the timely filing of such Schedule 13G 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: March 8, 2013


V. PREM WATSA

/s/ V. Prem Watsa


1109519 ONTARIO LIMITED

By:	/s/ V. Prem Watsa
	Name:	V. Prem Watsa
	Title:	President


THE SIXTY TWO INVESTMENT COMPANY LIMITED

By:	/s/ V. Prem Watsa
	Name:	V. Prem Watsa
	Title:	President


810679 ONTARIO LIMITED

By:	/s/ V. Prem Watsa
	Name:	V. Prem Watsa
	Title:	President


FAIRFAX FINANCIAL HOLDINGS LIMITED

By:	/s/ Paul Rivett
	Name:	Paul Rivett
	Title:	Vice President, Operations


ODYSSEY REINSURANCE COMPANY

By:	/s/ Kirk M. Reische
	Name:	Kirk M. Reische
	Title:	Vice President

COLOMBIA ENERGY RESOURCES, INC. SC 13G/A