Attempt Number: 4
Error Message: Action not unique compared to other actions chosen from this state before. Choose a new action

Action Reasoning:
We need to move the fast elevator fast1 up to floor n4 to allow passenger p4 to leave, aligning with the next steps in the goal plan.

New State Description:
- fast0: At floor n0, 0/2 passengers.- fast1: At floor n4, 2/2 passengers (p5 and p4 on board).- slow0-0: At floor n2, 0/1 passengers.- p0: On floor n2.- p1: On floor n1.- p2: On floor n5.- p3: On floor n5.- p4: On board fast1.- p5: On board fast1.- p6: On floor n2.

Action Chosen:
(move-up-fast fast1 n2 n4)
