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

class Main {
    public static void main(final String[] args) {
        Scanner scan = new Scanner(System.in);
        int N = scan.nextInt();
        Integer[] a = new Integer[N];
        for (int i = 0; i < N; i++) {
            a[i] = scan.nextInt();
        }
        Arrays.sort(a, Comparator.reverseOrder());
        int alice_total = 0;
        int bob_total = 0;
        for (int k = 0; k<N; k++) {
            if (k%2 == 0) {
                alice_total+=a[k];
            } else {
                bob_total += a[k];
            }
        }
        System.out.println(alice_total - bob_total);
    }
}

/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