Table:
Number of Shares (thousands)	Weighted-Average Remaining Vesting Term (years)

Nonvested as of December 31, 2018	5,974	$6.51

Granted	3,288	$6.74

Released	(1,774)	$6.60

Canceled	(1,340)	$6.57

Nonvested as of December 31, 2019	6,148	$6.59	1.81

A table may have multiple merged cells and we can represent a merged cell region by a JSON {'top-left':(R1, C1), 'bottom-right':(R2, C2)}. Here, '(R1, C1)' and '(R2, C2)' denote the coordinates (row_id, column_id) of the top-left and bottom-right cells of the merged regions, respectively. Now, based on the shown table image, please find all merged cells in this table and return their representations in the above format. Keep in mind that row and column IDs start from 1.

This table does not contain any merged cells.