import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;

public 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();
		}
		int alice = 0, bob = 0;

		Arrays.sort(a, Collections.reverseOrder());

		for (int i = 0; i < n; i++) {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		}

		System.out.println(alice - bob);
	}
} import java.util.Arrays; Arrays java.util import java.util.Collections; Collections java.util import java.util.Scanner; Scanner java.util public 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();
		}
		int alice = 0, bob = 0;

		Arrays.sort(a, Collections.reverseOrder());

		for (int i = 0; i < n; i++) {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		}

		System.out.println(alice - bob);
	}
} 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();
		}
		int alice = 0, bob = 0;

		Arrays.sort(a, Collections.reverseOrder());

		for (int i = 0; i < n; i++) {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		}

		System.out.println(alice - bob);
	} 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();
		}
		int alice = 0, bob = 0;

		Arrays.sort(a, Collections.reverseOrder());

		for (int i = 0; i < n; i++) {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		}

		System.out.println(alice - bob);
	} 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 int alice = 0 alice 0 bob = 0; bob 0 Arrays.sort(a, Collections.reverseOrder()) Arrays.sort Arrays a Collections.reverseOrder() Collections.reverseOrder Collections for (int i = 0; i < n; i++) {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		} {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		} alice += a[i] alice a[i] a i i++ i if (i == n) {
				break;
			} i == n i n {
				break;
			} break; 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 String[] args args public 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();
		}
		int alice = 0, bob = 0;

		Arrays.sort(a, Collections.reverseOrder());

		for (int i = 0; i < n; i++) {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		}

		System.out.println(alice - bob);
	}
} public 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();
		}
		int alice = 0, bob = 0;

		Arrays.sort(a, Collections.reverseOrder());

		for (int i = 0; i < n; i++) {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		}

		System.out.println(alice - bob);
	}
} Main
import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;

public 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();
		}
		int alice = 0, bob = 0;

		Arrays.sort(a, Collections.reverseOrder());

		for (int i = 0; i < n; i++) {
			alice += a[i];
			i++;
			if (i == n) {
				break;
			}
			bob += a[i];
		}

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