Starting state: there are 5 stacks: - Stack 1: purple block (alone) - Stack 2: green block (alone) - Stack 3: orange block (alone) - Stack 4: yellow block (alone) - Stack 5: blue block (alone) Ending state: there are 4 stacks: - Stack 1: purple block (alone) - Stack 2: green block (alone) - Stack 3: blue block (alone) - Stack 4: yellow block, orange block, from bottom to top