What is the total amount of the top 2 categories of accrued liabilities in 2019?
{"Advances": {"2019": 500, "2018": "-"}, "Board compensation": {"2019": 413, "2018": 413}, "Other accrued expenses": {"2019": 168, "2018": 150}, "": {"2019": 1081, "2018": 563}}
total_advances = df["Advances"]["2019"]
total_board_compensation = df["Board compensation"]["2019"]
answer = total_advances + total_board_compensation