import java.util.*;

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 Alice = 0;
        int Bob = 0;
        for (int i=0; i < n; i+=2) {
            Alice += a[i];
        }
        for (int i=1; i<n; i+=2) {
            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