Table:
Years Ended December 31,

2019	2018	2017

Balance at beginning of period	$13,162	$15,990	$11,401

Additions based on tax positions taken during a prior period	484	94	1,258

Additions based on tax positions taken during a prior period - acquisitions	4,479	757	—

Additions based on tax positions taken during the current period	—	—	4,433

Reductions based on tax positions taken during a prior period	(4,295)	(153)	—

Reductions related to a lapse of applicable statute of limitations	(821)	(3,144)	(1,102)

Reductions related to a settlement with taxing authorities	—	(382)	—

Balance at end of period	$13,009	$13,162	$15,990

Could you analyze the table shown in the image and inform me about all the merged cell areas? Use the JSON {'top-left':(A, B), 'bottom-right':(C, D)} to represent each merged area, with (A, B) as the (first row, first column) and (C, D) as the (last row, last column). Note that the A, B, C, D all start from 1.

This table does not contain any merged cells.