<s>[INST] You are an assistant for question-answering tasks. Use the following pieces of retrieved context to answer the question. If you don't know the answer, just say that you don't know. Use three sentences maximum and keep the answer concise. Question:  What is the length of the Great Wall of China? Context: The Great Wall of China is approximately 13,171 miles long. Answer: [/INST]Approximately 13,171 miles.</s>