Solve the problem with self-verification. After each reasoning step, you MUST verify it before proceeding. If verification fails, you MUST redo that step.

FORMAT RULES (follow exactly):
- Label each reasoning step as [R1], [R2], etc.
- Immediately after each [Rn], write [V-Rn] to verify that step.
- In [V-Rn], follow CRITICAL VERIFICATION RULE:
A reasoning step is valid only if every logical constraint is explicitly derived from previous steps. 
Treat any leap in logic or 'hallucinated' intermediate values as an immediate grounds for refutation.
- End [V-Rn] with exactly one of: PASS or FAIL
- If FAIL: redo the step as [Rn'] (revised), then verify again as [V-Rn'].
- You may retry a step at most 2 times. If it fails twice, flag it and proceed.
- Only move to [R(n+1)] after the current step passes verification.

OUTPUT FORMAT:
[Question]: <restate the question>
[R1]: <first reasoning step>
[V-R1]: <verify R1> → PASS or FAIL
[R1']: <revised R1, only if V-R1 failed>
[V-R1']: <verify revised R1> → PASS or FAIL
[R2]: <next reasoning step>
[V-R2]: <verify R2> → PASS or FAIL
...
[Rn]: <final reasoning step>
[V-Rn]: <verify Rn> → PASS or FAIL
[Answer]: <your final answer>

EXAMPLE:
[Question]: A store offers 20% off, then an additional 15% off the discounted price. What is the total discount on a $200 item?
[R1]: Apply first discount: $200 × 0.20 = $40 off, so price becomes $200 - $40 = $160.
[V-R1]: 20% of 200 is 40. 200 - 40 = 160. → PASS
[R2]: Apply second discount: $160 × 0.15 = $24 off, so price becomes $160 - $24 = $136.
[V-R2]: 15% of 160 is 24. 160 - 24 = 136. → PASS
[R3]: Total discount: $200 - $136 = $74. As percentage: 74 / 200 = 32%.
[V-R3]: 200 - 136 = 64, not 74. → FAIL
[R3']: Total discount: $200 - $136 = $64. As percentage: 64 / 200 = 32%.
[V-R3']: 200 - 136 = 64. 64 / 200 = 0.32 = 32%. → PASS
[Answer]: The total discount is $64, which is 32%.

Now solve:
{question}