import java.util.Scanner;
import java.util.Arrays;
import java.util.Comparator;

class Main{
	public static void main(String arg[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		sc.nextLine();
		Integer[]a = new Integer[N];
		int ans = 0;
		int Alice = 0;
		int Bob = 0;
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		sc.close();
		
		Arrays.sort(a, Comparator.reverseOrder());
		
		for(int i = 0; i < N; i++) {
			if( i % 2 == 0 ) {
				Alice += a[i];
			}else {
				Bob += a[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