<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:  How long is the Great Wall of China? Context: The Great Wall of China is about 13,171 miles (21,196 kilometers)长。 Answer: [/INST]About 13,171 miles (21,196 kilometers).</s>