SCHEDULE 13G

EXHIBIT A

RELEVANT SUBSIDIARIES AND MEMBERS OF FILING GROUP

PARENT HOLDING COMPANIES OR CONTROL PERSONS:

Warren E. Buffett (an individual who may be deemed to control Berkshire Hathaway Inc.)

Berkshire Hathaway Inc.

GEICO Corporation

INSURANCE COMPANIES AS DEFINED IN SECTION 3(a)(19) OF THE ACT:

National Indemnity Company

Government Employees Insurance Company

GEICO Indemnity Company

National Fire & Marine Insurance Company

EMPLOYEE BENEFIT PLANS IN ACCORDANCE WITH § 240.13d-1-(b)(1)(ii)(F)

FlightSafety International Inc. Retirement Income Plan

Fruit of the Loom Pension Trust

GEICO Corporation Pension Plan Trust

Johns Manville Corporation Master Pension Trust

BNSF Master Retirement Trust

General Re Corp. Employee Retirement Trust

Lubrizol Corp. Master Trust Pension

OTHER MEMBER OF FILING GROUP

R. Ted Weschler