请列出世界上最高的山峰的前五名，并用JSON格式返回。
user
```json
{
  "highest_mountains": [
    {
      "rank": 1,
      "name": "珠穆朗玛峰",
      "elevation": "8848.86米",
      "location": "喜马拉雅山脉，中国/尼泊尔边界"
    },
    {
      "rank": 2,
      "name": "乔戈里峰",
      "elevation": "8611米",
      "location": "喀喇昆仑山脉，巴基斯坦"
    },
    {
      "rank": 3,
      "name": "干城章嘉峰",
      "elevation": "8586米",
      "location": "喜马拉雅山脉，尼泊尔/印度边界"
    },
    {
      "rank": 4,
      "name": "洛子峰",
      "elevation": "8516米",
      "location": "喜马拉雅山脉，中国/尼泊尔边界"
    },
    {
      "rank": 5,
      "name": "马卡鲁峰",
      "elevation": "8485米",
      "location": "喜马拉雅山脉，中国/尼泊尔边界"
    }
  ]
}
```
assistant