Can you please help me with this ultimatum game ?

Player A must split 100$ with Player B (1-99$)

B can accept the offer and the game ends or refuse

If B refuse we get to second stage of the game with probability P or the game ends with probability 1-P and both gets 0$

In the second stage B must split X$ (X<=100) with A but A con only accept the offer

They both know P and X before the game starts

So what do you think is the optimal solution for the game?

Do the risk attitude of A and B matter in the solution ?