What is the change in Balance of unrecognized tax benefits as of January 1, from Years Ended December 31, 2018 to 2019?
{"Balance of unrecognized tax benefits as of January 1,": {"2019": 1226, "2018": 37240}, "Increases for positions taken in prior years": {"2019": 1353, "2018": 657}, "Rate change": {"2019": -84, "2018": "\u2014"}, "Amount of decreases related to settlements": {"2019": "\u2014", "2018": -36671}, "Balance of unrecognized tax benefits as of December 31,": {"2019": 2495, "2018": 1226}}
balance_2019 = df["Balance of unrecognized tax benefits as of January 1,"]["2019"]
balance_2018 = df["Balance of unrecognized tax benefits as of January 1,"]["2018"]
answer = balance_2019 - balance_2018