## BPC 1 J3 - Group Project

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Points: 5
Time limit: 2.0s
Memory limit: 512M

Author:
Problem type

You are a teacher deciding on pairs for a group project. You have students that are given a quality score . For each pair, you will receive complaints, where is the difference in quality between the two students. Output the minimum number of complaints you can receive.

#### Constraints

for all integer from to .

#### Input Specification

The first line contains an integer, .

The second line contains integers, the being .

#### Output Specification

Output a single line containing an integer, the number of complaints if you optimally pair students to minimize complaints.

Note: the answer might not fit in a 32-bit integer.

#### Sample Input

3
1 7 4 6 10 9

#### Sample Output

5