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();
		}
		sc.close();
		Arrays.sort(a, Collections.reverseOrder());
		int A = a[0], B = 0;

		for (int i = 1; i < N; i++) {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		}
		System.out.println(A - B);
	}
} 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();
		}
		sc.close();
		Arrays.sort(a, Collections.reverseOrder());
		int A = a[0], B = 0;

		for (int i = 1; i < N; i++) {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		}
		System.out.println(A - B);
	}
} 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();
		}
		sc.close();
		Arrays.sort(a, Collections.reverseOrder());
		int A = a[0], B = 0;

		for (int i = 1; i < N; i++) {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		}
		System.out.println(A - B);
	} 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();
		}
		sc.close();
		Arrays.sort(a, Collections.reverseOrder());
		int A = a[0], B = 0;

		for (int i = 1; i < N; i++) {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		}
		System.out.println(A - B);
	} 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 sc.close() sc.close sc Arrays.sort(a, Collections.reverseOrder()) Arrays.sort Arrays a Collections.reverseOrder() Collections.reverseOrder Collections int A = a[0] A a[0] a 0 B = 0; B 0 for (int i = 1; i < N; i++) {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		} int i = 1; int i = 1; i 1 i < N i N i++ i++ i {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		} {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		} if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			} i % 2 == 0 i % 2 i 2 0 {
				A += a[i];
			} A += a[i] A a[i] a i {
				B += a[i];
			} B += a[i] B a[i] a i System.out.println(A - B) System.out.println System.out System System.out A - B A B 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();
		}
		sc.close();
		Arrays.sort(a, Collections.reverseOrder());
		int A = a[0], B = 0;

		for (int i = 1; i < N; i++) {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		}
		System.out.println(A - B);
	}
} 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();
		}
		sc.close();
		Arrays.sort(a, Collections.reverseOrder());
		int A = a[0], B = 0;

		for (int i = 1; i < N; i++) {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		}
		System.out.println(A - B);
	}
} 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();
		}
		sc.close();
		Arrays.sort(a, Collections.reverseOrder());
		int A = a[0], B = 0;

		for (int i = 1; i < N; i++) {
			if (i % 2 == 0) {
				A += a[i];
			} else {
				B += a[i];
			}
		}
		System.out.println(A - B);
	}
}
