Parent State ID: 3
State Depth: 3
Action Taken: unstack(d, a)
Action Reasoning: To move towards the goal state, we need to stack block 'a' on block 'c'. First, we must clear block 'a' by unstacking block 'd' from it.
State Description: There are four blocks: a, b, c, and d. The hand is holding block d. Block a is on the table and clear. Block b is on the table and clear. Block c is on the table and clear. Block d is no longer on block a.
Action Path: ['unstack(c, d)', 'put-down(c)', 'unstack(d, a)']
