（a）
curl https://api.openai.com/v1/chat/completions  \
-H "Content-Type: application/json"  \
-H "Authorization: Bearer ${OPENAI_API_KEY}"  \
-d '{ 	"model": "gpt-4o-mini",
        "messages": [
               {"role": "system", "content": "You are a helpful assistant."},
               {"role": "user", "content": "富士山の高さは？"}
               ]
}'

（b）
{
         "id": "chatcmpl-C69EJxZTvu8HoWLht5w4ClGWio50Z",
         "object": "chat.completion",
         "created": 1755581483,
         "model": "gpt-4o-mini",
         "choices": [ {
                "index": 0, "message": {
                       "role": "assistant",
                "content": "富士山の高さは3,776メートルです。",
                "refusal": null,
                "annotations": [] },
                "logprobs": null,
                "finish_reason": "stop" 
         } ],

         "usage": {
                "prompt_tokens": 24,
                "completion_tokens": 14,
                "total_tokens": 38,
                "prompt_tokens_details": {
                       "cached_tokens": 0,
                       "audio_tokens": 0
                },

         "completion_tokens_details": {
                "reasoning_tokens": 0,
                "audio_tokens": 0,
                "accepted_prediction_tokens": 0, "rejected_prediction_tokens": 0 }
         },

"service_tier": "default",
"system_fingerprint": "fp_80956533cb"
}
