import java.util.*;

public 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, Collections.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];
			}
		}
		int sa = Alice - Bob;
		System.out.println(sa);
		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