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();
    }
} import java.util.*; util.* java 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();
    }
} 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();
    } main {

        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();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int ans = 0; ans 0 Integer 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 bob = 0; bob 0 for (int i = 0; i < n; i++) {
            if (i % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            if (i % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
        } {
            if (i % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
        } if (i % 2 == 0)
                alice += a[i];
            else
                bob += a[i]; i % 2 == 0 i % 2 i 2 0 alice += a[i] alice a[i] 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) 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();
    }
}
