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();
    }
} import java.util.*; util.* java 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();
    }
} 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();
    } main {
        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();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc Integer a[] = new Integer[n]; a new Integer[n] n for (int i=0; i<n; i++) {
            a[i] = sc.nextInt();
        } int i=0; int i=0; i 0 i<n i n i++ i++ i {
            a[i] = sc.nextInt();
        } {
            a[i] = sc.nextInt();
        } a[i] = sc.nextInt() a[i] a i sc.nextInt() sc.nextInt sc Arrays.sort(a, Comparator.reverseOrder()) Arrays.sort Arrays a Comparator.reverseOrder() Comparator.reverseOrder Comparator int Alice = 0; Alice 0 int Bob = 0; Bob 0 for (int i=0; i < n; i+=2) {
            Alice += a[i];
        } int i=0; int i=0; i 0 i < n i n i+=2 i+=2 i 2 {
            Alice += a[i];
        } {
            Alice += a[i];
        } Alice += a[i] Alice a[i] a i for (int i=1; i<n; i+=2) {
            Bob += a[i];
        } int i=1; int i=1; i 1 i<n i n i+=2 i+=2 i 2 {
            Bob += a[i];
        } {
            Bob += a[i];
        } Bob += a[i] Bob a[i] a i System.out.println(Alice-Bob) System.out.println System.out System System.out Alice-Bob Alice Bob sc.close() sc.close sc String[] args args
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();
    }
}