You will be given a definition of a task first, then some input of the task.
Given a passage with a question and an answer to that question, classify if the answer actually answers the question into 'yes' or 'no'. Output 'yes' if the answer answers the question and output 'no' if the answer does not answer the question.

Question: Do changes in middle cerebral artery velocity after carotid endarterectomy identify patients at high-risk of suffering intracranial haemorrhage or stroke due to hyperperfusion syndrome?
Answer: We were unable to demonstrate that significant increases in MCAV and PI were able to predict patients at increased risk of suffering a post-operative stroke due to HS or ICH. The provision of written guidance for managing PEH in Group 2 patients was associated with virtual abolition of ICH/HS.
Output:
no