Table:
Year Ended December 31,	Year Ended December 31,	Year Ended December 31,	Variation	Variation

2019	2018	2017	2019 vs 2018	2018 vs 2017

(In millions)	(In millions)	(In millions)

Cost of sales	$(5,860)	$(5,803)	$(5,075)	1.0%	(14.3)%

Gross profit	$3,696	$3,861	$3,272	(4.3)%	18.0%

Gross margin (as percentage of net revenues)	38.7%	40.0%	39.2%	-130 bps	+80 bps

Inspect the given table and provide the values of cells found at the specified positions, determined by row and column indices. Show the cell value in the JSON format {"row_id":"m", "column_id":"n", "cell_value":"<Corresponding Cell Value>"}.
Positions:
row 6 and column 1,
row 4 and column 4,

The target cell values are as follows:
{"row_id":"6", "column_id":"1", "cell_value":"Gross margin (as percentage of net revenues)"}
{"row_id":"4", "column_id":"4", "cell_value":"$(5,075)"}