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

Action Reasoning:
Since we have already boarded passenger p2 on fast1, the next step in the plan is to move fast1 up to floor n4 to board passenger p3.

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

Action Chosen:
(move-up-fast fast1 n3 n4)
