Exhibit A

JOINT FILING AGREEMENT

The undersigned hereby agree that the foregoing statement on Schedule 13G is filed on behalf of each of the undersigned in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, and that all subsequent amendments to this statement on Schedule 13G may be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements.

Dated: February 14, 2019

DEAL VANGUARD LIMITED
By:	/s/ Chi Hin Jacob Lee
	Name: Chi Hin Jacob Lee
	Title:   Director
CHOW TAI FOOK ENTERPRISES LIMITED
By:	/s/ On Yip Patrick Tsang
	Name: On Yip Patrick Tsang
	Title:   Director
CHOW TAI FOOK (HOLDING) LIMITED
By:	/s/ On Yip Patrick Tsang
	Name: On Yip Patrick Tsang
	Title:   Director
CHOW TAI FOOK CAPITAL LIMITED
By:	/s/ Kar Shing Cheng
	Name: Kar Shing Cheng
	Title:   Director