import java.util.*;

public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		List<Integer> list = new ArrayList<>();
		for(int i=0; i<n; i++){
			list.add(sc.nextInt());
		}
		list.sort(Comparator.reverseOrder());
		int alice = 0, bob = 0;
		for(int i=0; i<n; i++){
			if(i % 2 == 0){
				alice += list.get(i);
			}else{
				bob += list.get(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