What is the difference in total capital expenditure for restaurants and total capital expenditure for corporate services in 2018?
{"Restaurants: -- Restaurant facility expenditures": {"2019": 9202, "2018": 17949}, "Restaurants: -- Purchases of assets intended for sale or sale and leaseback": {"2019": 21660, "2018": 5497}, "Restaurants: -- New restaurants": {"2019": 1381, "2018": 2088}, "Restaurants: -- Other, including information technology": {"2019": 3597, "2018": 7572}, "Restaurants: -- ": {"2019": 35840, "2018": 33106}, "Corporate Services: -- Information technology": {"2019": 9405, "2018": 4584}, "Corporate Services: -- Other, including facility improvements": {"2019": 2404, "2018": 152}, "Corporate Services: -- ": {"2019": 11809, "2018": 4736}, "Corporate Services: -- Total capital expenditures": {"2019": 47649, "2018": 37842}}
restaurants_2018 = df["Restaurants: -- "]["2018"]
corporate_services_2018 = df["Corporate Services: -- "]["2018"]
answer = restaurants_2018 - corporate_services_2018