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

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;
		int sum=0;
		for(int i=0;i<n;i++) {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		}
		sum=alice-bob;
		System.out.println(sum);
	}
}

/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