What is the difference between the amount of gross deferred tax assets in 2018 and 2019?
{"Deferred tax assets -- Net operating loss and tax credit carryforwards": {"2019": 1045, "2018": 1417}, "Deferred tax assets -- Accrued salaries, wages, and benefits": {"2019": 122, "2018": 163}, "Deferred tax assets -- Property, plant, and equipment": {"2019": 80, "2018": "\u2014"}, "Deferred tax assets -- Other": {"2019": 110, "2018": 115}, "Deferred tax assets -- Gross deferred tax assets": {"2019": 1357, "2018": 1695}, "Deferred tax assets -- Less valuation allowance": {"2019": -277, "2018": -228}, "Deferred tax assets -- Deferred tax assets, net of valuation allowance": {"2019": 1080, "2018": 1467}, "Deferred tax liabilities -- Product and process technology": {"2019": -138, "2018": -62}, "Deferred tax liabilities -- Property, plant, and equipment": {"2019": "\u2014", "2018": -173}, "Deferred tax liabilities -- Other": {"2019": -109, "2018": -213}, "Deferred tax liabilities -- Deferred tax liabilities": {"2019": -247, "2018": -448}, "Deferred tax liabilities -- Net deferred tax assets": {"2019": 833, "2018": 1019}, "Reported as -- Deferred tax assets": {"2019": 837, "2018": 1022}, "Reported as -- Deferred tax liabilities (included in other noncurrent liabilities)": {"2019": -4, "2018": -3}, "Reported as -- Net deferred tax assets": {"2019": 833, "2018": 1019}}
gross_deferred_tax_assets_2018 = df["Deferred tax assets -- Gross deferred tax assets"]["2018"]
gross_deferred_tax_assets_2019 = df["Deferred tax assets -- Gross deferred tax assets"]["2019"]
answer = gross_deferred_tax_assets_2018 - gross_deferred_tax_assets_2019