You are a teacher deciding on pairs for a group project. You have ~2N~ students that are given a quality score ~q_i~. For each pair, you will receive ~X~ complaints, where ~X~ is the difference in quality between the two students. Output the minimum number of complaints you can receive.

Constraints

~1 \le N \le 10^6~

~1 \le q_i \le 10^9~ for all integer ~i~ from ~1~ to ~2N~.

Input Specification

The first line contains an integer, ~N~.

The second line contains ~2N~ integers, the ~i^\text{th}~ being ~q_i~.

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