1086. High Five

Given a list of scores of different students, return the average score of each student's top five scores in the order of each student's id.

Each entry items[i] has items[i][0] the student's id, and items[i][1] the student's score.  The average score is calculated using integer division.

Example 1:

Input: [[1,91],[1,92],[2,93],[2,97],[1,60],[2,77],[1,65],[1,87],[1,100],[2,100],[2,76]]
Output: [[1,87],[2,88]]
Explanation: 
The average of the student with id = 1 is 87.
The average of the student with id = 2 is 88.6. But with integer division their average converts to 88.

Note:

1. 1 <= items.length <= 1000
2. items[i].length == 2
3. The IDs of the students is between 1 to 1000
4. The score of the students is between 1 to 100
5. For each student, there are at least 5 scores