import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    Integer[] a = new Integer[n];
    for (int i = 0; i < n; i++) {
      a[i] = sc.nextInt();
    }
    Arrays.sort(a, Comparator.reverseOrder());
    int alice = 0;
    int bob = 0;
    for (int i = 0; i < n; i++) {
      if (i % 2 == 0) {
        alice += a[i];
      } else {
        bob += a[i];
      }
    }
    System.out.println(alice - bob);
  }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz