import 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();
		}
		Arrays.sort(a, Collections.reverseOrder());
		int Alice = 0;
		int Bob = 0;
		for (int i = 0; i < n; i++) {
			if (i % 2 == 0) {
				Alice += a[i];
			} else {
				Bob += a[i];
			}
		}
		int sa = Alice - Bob;
		System.out.println(sa);
		sc.close();
	}

} import java.util.*; util.* java 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();
		}
		Arrays.sort(a, Collections.reverseOrder());
		int Alice = 0;
		int Bob = 0;
		for (int i = 0; i < n; i++) {
			if (i % 2 == 0) {
				Alice += a[i];
			} else {
				Bob += a[i];
			}
		}
		int sa = Alice - Bob;
		System.out.println(sa);
		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, Collections.reverseOrder());
		int Alice = 0;
		int Bob = 0;
		for (int i = 0; i < n; i++) {
			if (i % 2 == 0) {
				Alice += a[i];
			} else {
				Bob += a[i];
			}
		}
		int sa = Alice - Bob;
		System.out.println(sa);
		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, Collections.reverseOrder());
		int Alice = 0;
		int Bob = 0;
		for (int i = 0; i < n; i++) {
			if (i % 2 == 0) {
				Alice += a[i];
			} else {
				Bob += a[i];
			}
		}
		int sa = Alice - Bob;
		System.out.println(sa);
		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, Collections.reverseOrder()) Arrays.sort Arrays a Collections.reverseOrder() Collections.reverseOrder Collections int Alice = 0; Alice 0 int 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] Alice a[i] a i {
				Bob += a[i];
			} Bob += a[i] Bob a[i] a i int sa = Alice - Bob; sa Alice - Bob Alice Bob System.out.println(sa) System.out.println System.out System System.out sa sc.close() sc.close sc 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();
		}
		Arrays.sort(a, Collections.reverseOrder());
		int Alice = 0;
		int Bob = 0;
		for (int i = 0; i < n; i++) {
			if (i % 2 == 0) {
				Alice += a[i];
			} else {
				Bob += a[i];
			}
		}
		int sa = Alice - Bob;
		System.out.println(sa);
		sc.close();
	}

} 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();
		}
		Arrays.sort(a, Collections.reverseOrder());
		int Alice = 0;
		int Bob = 0;
		for (int i = 0; i < n; i++) {
			if (i % 2 == 0) {
				Alice += a[i];
			} else {
				Bob += a[i];
			}
		}
		int sa = Alice - Bob;
		System.out.println(sa);
		sc.close();
	}

} Main
import 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();
		}
		Arrays.sort(a, Collections.reverseOrder());
		int Alice = 0;
		int Bob = 0;
		for (int i = 0; i < n; i++) {
			if (i % 2 == 0) {
				Alice += a[i];
			} else {
				Bob += a[i];
			}
		}
		int sa = Alice - Bob;
		System.out.println(sa);
		sc.close();
	}

}
