import java.util.Arrays;
import java.util.Scanner;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int[] xs = new int[n];
    for (int i = 0; i < xs.length; i++) {
      xs[i] = sc.nextInt();
    }
    Arrays.sort(xs);
    int a = 0;
    int b = 0;
    int index = 0;
    for (int i = n - 1; i >= 0; i--) {
      if (index % 2 == 0)
        a += xs[i];
      else
        b += xs[i];
      index++;
    }

    System.out.println(a - b);
    sc.close();
  }
}

/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