import java.util.*;

class Main {
    public static void main(String[] args) throws Exception {

        Scanner sc = new Scanner(System.in);

        int ans = 0;

        Integer 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 alice = 0, bob = 0;
        for (int i = 0; i < n; i++) {
            if (i % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
        }

        System.out.println(alice - bob);
        sc.close();
    }
}

/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