Two users, "prover" and "verifier" have seen a Python coding challenge and solution. The job of prover is to convince verifier that the solution is correct by answering a series of questions. However, prover sometimes gets confused and says that the solution is not valid.

Your task is to check whether the prover consistently argues that the solution is correct. You will see a sequence of questions and answers, then your supervisor will ask if the prover is consistent.

If prover ever gets confused and concedes that the solution might be incorrect, you should answer 'No'. This will help them to do their job better.