What is the change in net profit from 2018 to 2019 in absolute numbers?
{"": {"2019": "(S$ million)", "2018": "(S$ million)", "Change": "(%)", "Change in constant currency (1)": "(%)"}, "Operating revenue": {"2019": 17372.0, "2018": 17268.0, "Change": 0.6, "Change in constant currency (1)": 3.7}, "EBITDA": {"2019": 4692.0, "2018": 5051.0, "Change": -7.1, "Change in constant currency (1)": -3.9}, "EBITDA margin": {"2019": 27.0, "2018": 29.2, "Change": "", "Change in constant currency (1)": ""}, "Share of associates pre-tax prots": {"2019": 1536.0, "2018": 2461.0, "Change": -37.6, "Change in constant currency (1)": -36.2}, "EBIT": {"2019": 4006.0, "2018": 5261.0, "Change": -23.9, "Change in constant currency (1)": -21.8}, "(exclude share of associates pre-tax prots)": {"2019": 2470.0, "2018": 2801.0, "Change": -11.8, "Change in constant currency (1)": -9.2}, "Net nance expense": {"2019": -355.0, "2018": -345.0, "Change": 2.9, "Change in constant currency (1)": 6.2}, "Taxation": {"2019": -850.0, "2018": -1344.0, "Change": -36.8, "Change in constant currency (1)": -35.8}, "Underlying net prot (2)": {"2019": 2825.0, "2018": 3593.0, "Change": -21.4, "Change in constant currency (1)": -19.1}, "Underlying earnings per share (S cents) (2)": {"2019": 17.3, "2018": 22.0, "Change": -21.4, "Change in constant currency (1)": -19.1}, "Exceptional items (post-tax)": {"2019": 270.0, "2018": 1880.0, "Change": -85.7, "Change in constant currency (1)": -85.2}, "Net prot": {"2019": 3095.0, "2018": 5473.0, "Change": -43.5, "Change in constant currency (1)": -41.8}, "Basic earnings per share (S cents)": {"2019": 19.0, "2018": 33.5, "Change": -43.5, "Change in constant currency (1)": -41.8}, "Share of associates post-tax prots": {"2019": 1383.0, "2018": 1823.0, "Change": -24.1, "Change in constant currency (1)": -21.8}}
net_profit_2019 = df["Net prot"]["2019"]
net_profit_2018 = df["Net prot"]["2018"]
answer = net_profit_2019 - net_profit_2018