
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		List<Integer> list = new ArrayList<>();
		int n = sc.nextInt();
		for(int i = 0; i < n; i++) {
			list.add(sc.nextInt());
		}
		Collections.sort(list);
		list.sort(Comparator.reverseOrder());
		int a = 0;
		int b = 0;
		for(int i = 0; i < list.size(); i++) {
			if(i % 2 == 0) {
				a += list.get(i);
			} else {
				b += list.get(i);
			}
		}
		System.out.println(a - b);
	}

}

/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