import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		
		try (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++) {
				if (i % 2 == 0) {
					Alice += a[i];
				} else {
					Bob += a[i];
				}
			}
			
			System.out.println(Alice - Bob);
		}

	}

} import java.util.Arrays; Arrays java.util import java.util.Comparator; Comparator java.util import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		
		try (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++) {
				if (i % 2 == 0) {
					Alice += a[i];
				} else {
					Bob += a[i];
				}
			}
			
			System.out.println(Alice - Bob);
		}

	}

} Main public static void main(String[] args) {
		
		try (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++) {
				if (i % 2 == 0) {
					Alice += a[i];
				} else {
					Bob += a[i];
				}
			}
			
			System.out.println(Alice - Bob);
		}

	} main {
		
		try (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++) {
				if (i % 2 == 0) {
					Alice += a[i];
				} else {
					Bob += a[i];
				}
			}
			
			System.out.println(Alice - Bob);
		}

	} try (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++) {
				if (i % 2 == 0) {
					Alice += a[i];
				} else {
					Bob += a[i];
				}
			}
			
			System.out.println(Alice - Bob);
		} {
			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++) {
				if (i % 2 == 0) {
					Alice += a[i];
				} else {
					Bob += a[i];
				}
			}
			
			System.out.println(Alice - Bob);
		} Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) 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++) {
				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 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) {
		
		try (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++) {
				if (i % 2 == 0) {
					Alice += a[i];
				} else {
					Bob += a[i];
				}
			}
			
			System.out.println(Alice - Bob);
		}

	}

} public class Main {

	public static void main(String[] args) {
		
		try (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++) {
				if (i % 2 == 0) {
					Alice += a[i];
				} else {
					Bob += a[i];
				}
			}
			
			System.out.println(Alice - Bob);
		}

	}

} Main
import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		
		try (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++) {
				if (i % 2 == 0) {
					Alice += a[i];
				} else {
					Bob += a[i];
				}
			}
			
			System.out.println(Alice - Bob);
		}

	}

}