import java.util.Arrays;
import java.util.Comparator;
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,Comparator.reverseOrder());
		int AliceScore = 0;
		int BobScore = 0;
		for(int c=0;c<a.length;c++) {
		if(c%2==0) {
			AliceScore += a[c];
		}
		else {
			BobScore += a[c];
		}
		}
		System.out.println(AliceScore-BobScore);
	}
}
/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