What is the change in cash and cash equivalents between 2019 and 2018?
{"Acquisitions 20172019 -- ": {"2019": 2019, "2018": 2018, "2017": 2017}, "Acquisitions 20172019 -- Total consideration, including cash": {"2019": 1957, "2018": 1314, "2017": 62}, "Net assets acquired -- Cash and cash equivalents": {"2019": 142, "2018": 94, "2017": "\u2013"}, "Net assets acquired -- Property, plant and equipment": {"2019": 353, "2018": 4, "2017": 12}, "Net assets acquired -- Intangible assets": {"2019": 497, "2018": 481, "2017": 101}, "Net assets acquired -- Investments in associates": {"2019": 101, "2018": 64, "2017": "\u2013"}, "Net assets acquired -- Other assets": {"2019": 1357, "2018": 254, "2017": 1}, "Net assets acquired -- Provisions, incl. post-employment benefits": {"2019": 102, "2018": "\u2013", "2017": "\u2013"}, "Net assets acquired -- Other liabilities": {"2019": 743, "2018": 494, "2017": 25}, "Net assets acquired -- Total identifiable net assets": {"2019": 1605, "2018": 403, "2017": 139}, "Net assets acquired -- Costs recognized in net income": {"2019": 153, "2018": "\u2013", "2017": "\u2013"}, "Net assets acquired -- Goodwill": {"2019": 199, "2018": 911, "2017": 77}, "Net assets acquired -- Total": {"2019": 1957, "2018": 1314, "2017": 62}, "Net assets acquired -- Acquisition-related costs 1)": {"2019": 85, "2018": 24, "2017": 49}}
cash_and_cash_equivalents_2019 = df["Net assets acquired -- Cash and cash equivalents"]["2019"]
cash_and_cash_equivalents_2018 = df["Net assets acquired -- Cash and cash equivalents"]["2018"]
answer = cash_and_cash_equivalents_2019 - cash_and_cash_equivalents_2018