请以json格式输出关于一场 autumn marathon（秋季马拉松）的活动内容，包括日期、地点、费用、报名截止日期等。注意：本次活动的费用将根据报名时间进行分段收费。具体来说，在9月1日前报名的费用为1000元，在9月1日到9月15日之间报名的费用为1200元，9月15日之后报名的费用为1500元。同时，请附上一段不少于50字的活动介绍。
user
{
  "event": "Autumn Marathon",
  "date": "2023-10-21",
  "location": "Beijing Olympic Park",
  "registration deadlines and fees": {
    "before 2023-09-01": 1000,
    "2023-09-01 to 2023-09-15": 1200,
    "after 2023-09-15": 1500
  },
  "intro": "Autumn Marathon is a spectacular sporting event scheduled to take place in Beijing Olympic Park. Inviting participants from all over the world, the marathon invigorates the city with the spirit of endurance and determination, as runners immerse themselves in the enchanting autumn scenery. Join us for an unforgettable running experience, enhanced by beautiful views and a vibrant community atmosphere."
}
assistant