A bank money manager estimates that the bank will experience a liquidity deficit of $400 million with a probability of 10 percent, a liquidity deficit of $900 million with a probability of 20 percent, a liquidity surplus of $600 million with a probability of 30 percent and a liquidity surplus of $1200 with a probability of 40 percent over the next month. What is this bank's expected liquidity deficit or surplus over this next month