On the asset side, a bank has the following entries in the year $2023$:

Mortages: $$1200$

Mortgage$-$backed securities: $$1000$

Cash: $$300$

On the liability side, it has:

Deposits: $$500$

Short$-$term debt: $$1500$

long$-$term debt: $$300$

In $2024,$ some creditors that provide short$-$term funding do not want to lend to the bank anymore, so they demand that the bank pay back $$600$ out of the $$1500$ in short$-$term debt. The bank liquidates its cash to pay back its debt, but that is not enough. Therefore, it needs to liquidate some of its mortgage$-$backed securities$.$ These mortgage$-$backed securities are very illiquid, and the bank can liquidate them at only $50\%$ of their value.

What is the new net worth of the bank after liquidating the amount of mortgage$-$backed securities needed to exactly pay back the creditors who demand their money back?