Table:
As of December 31,

2019	2018

(Dollars in millions)

Deferred tax assets

Post-retirement and pension benefit costs	$1,169	1,111

Net operating loss carryforwards	3,167	3,445

Other employee benefits	134	162

Other	577	553

Gross deferred tax assets	5,047	5,271

Less valuation allowance	(1,319)	(1,331)

Net deferred tax assets	3,728	3,940

Deferred tax liabilities

Property, plant and equipment, primarily due to depreciation differences	(3,489)	(3,011)

Goodwill and other intangible assets	(3,019)	(3,303)

Other	—	(23)

Gross deferred tax liabilities	(6,508)	(6,337)

Net deferred tax liability	$(2,780)	(2,397)

The task is as follows:
Analyze the table in this image to find every merged cell. Return the regions of these merged cells in the JSON {'top-left':(X1, Y1), 'bottom-right':(X2, Y2)}, where '(X1, Y1)' and '(X2, Y2)' show the (row_id, column_id) of the top-left and bottom-right cells in these regions, respectively. The row and column IDs start from 1.

This table does not contain any merged cells.