What is the increase / (decrease) in total inventory in 2019 compared to 2018?
{"Flocks, net of accumulated amortization": {"June 1, 2019": 105536, "June 2, 2018": 96594}, "Eggs": {"June 1, 2019": 14318, "June 2, 2018": 17313}, "Feed and supplies": {"June 1, 2019": 52383, "June 2, 2018": 54737}, "": {"June 1, 2019": 172237, "June 2, 2018": 168644}}
june_1_2019 = df[""]["June 1, 2019"]
june_2_2018 = df[""]["June 2, 2018"]
answer = june_1_2019 - june_2_2018