EXHIBIT 2.1

CUSIP No.  Y75638109

AGREEMENT CONCERNING JOINT FILING

OF SCHEDULE 13D

The undersigned agree as follows:

(i) each of them is individually eligible to use the 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:  July 17, 2018

1

V. PREM WATSA
/s/ V. Prem Watsa
V. Prem Watsa
THE ONE ONE ZERO NINE HOLDCO 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
THE SIXTY THREE FOUNDATION
By:	/s/ V. Prem Watsa
	Name: V. Prem Watsa
	Title: Director

2

FAIRFAX FINANCIAL HOLDINGS LIMITED
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: President
FFHL GROUP LTD.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Director
FAIRFAX (BARBADOS) INTERNATIONAL CORP.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
WENTWORTH INSURANCE COMPANY LTD.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
HAMBLIN WATSA INVESTMENT COUNSEL LTD.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Managing Director

3

FAIRFAX (US) INC.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
ODYSSEY US HOLDINGS INC.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
ODYSSEY RE HOLDINGS CORP.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
ODYSSEY REINSURANCE COMPANY
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
1102952 B.C. UNLIMITED LIABILITY COMPANY
By:	/s/ Paul Rivett
	Name: Paul Rivett

4

	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
FAIRFAX FINANCIAL HOLDINGS (SWITZERLAND) GMBH
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
ALLIED WORLD ASSURANCE COMPANY HOLDINGS, GMBH
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
ALLIED WORLD ASSURANCE COMPANY HOLDINGS, LTD
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D

5

ALLIED WORLD ASSURANCE COMPANY, LTD
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D

6

ALLIED WORLD ASSURANCE HOLDINGS (IRELAND) LTD.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
ALLIED WORLD ASSURANCE HOLDINGS (U.S.) INC.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
ALLIED WORLD INSURANCE COMPANY
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
AW UNDERWRITERS INC.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D

7

ALLIED WORLD SPECIALTY INSURANCE COMPANY
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D

8

CRUM & FORSTER HOLDINGS CORP.
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
UNITED STATES FIRE INSURANCE COMPANY
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
ZENITH NATIONAL INSURANCE COMPANY
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D
ZENITH INSURANCE COMPANY
By:	/s/ Paul Rivett
	Name: Paul Rivett
	Title: Attorney-in-Fact pursuant to Power of Attorney attached to this Schedule 13D

9

RIVERSTONE HOLDINGS LIMITED
By:	/s/ Nicholas C. Bentley
	Name: Nicholas C. Bentley
	Title: Managing Director
RIVERSTONE INSURANCE (UK) LIMITED
By:	/s/ Nicholas C. Bentley
	Name: Nicholas C. Bentley
	Title: Director

10

BRIT LIMITED
By:	/s/ Mark Allan
	Name: Mark Allan
	Title: Chief Financial Officer and Director
BRIT INSURANCE HOLDINGS LIMITED
By:	/s/ Mark Allan
	Name: Mark Allan
	Title: Chief Financial Officer and Director
BRIT REINSURANCE (BERMUDA) LIMITED
By:	/s/ Mark Allan
	Name: Mark Allan
	Title: Director

11