What was the change in the net cost of computer equipment between 2018 and 2019?
{"Land": {"2019": 1, "2018": 1}, "Buildings": {"2019": 4, "2018": 4}, "Leasehold improvements": {"2019": 252, "2018": 248}, "Computer equipment": {"2019": 654, "2018": 700}, "Office furniture and other equipment": {"2019": 91, "2018": 99}, "Total cost of property and equipment": {"2019": 1002, "2018": 1052}, "Less accumulated depreciation": {"2019": -749, "2018": -770}, "Property and equipment, net": {"2019": 253, "2018": 282}}
computer_equipment_2019 = df["Computer equipment"]["2019"]
computer_equipment_2018 = df["Computer equipment"]["2018"]
answer = computer_equipment_2019 - computer_equipment_2018