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

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];

		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
		}
		int alice = 0;
		int bob = 0;
		Arrays.sort(a);
		for (int i = n - 1; i >= 0; i--) {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				bob += a[i];
			}
		}

		System.out.println(alice-bob);
	}
} import java.util.Arrays; Arrays 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();
		int a[] = new int[n];

		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
		}
		int alice = 0;
		int bob = 0;
		Arrays.sort(a);
		for (int i = n - 1; i >= 0; i--) {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				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();
		int a[] = new int[n];

		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
		}
		int alice = 0;
		int bob = 0;
		Arrays.sort(a);
		for (int i = n - 1; i >= 0; i--) {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				bob += a[i];
			}
		}

		System.out.println(alice-bob);
	} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];

		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
		}
		int alice = 0;
		int bob = 0;
		Arrays.sort(a);
		for (int i = n - 1; i >= 0; i--) {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				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 int a[] = new int[n]; a new int[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 int bob = 0; bob 0 Arrays.sort(a) Arrays.sort Arrays a for (int i = n - 1; i >= 0; i--) {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				bob += a[i];
			}
		} int i = n - 1; int i = n - 1; i n - 1 n 1 i >= 0 i 0 i-- i-- i {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				bob += a[i];
			}
		} {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				bob += a[i];
			}
		} if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				bob += a[i];
			} i % 2 == (n - 1) % 2 i % 2 i 2 (n - 1) % 2 (n - 1) n 1 2 {
				alice = alice + a[i];
			} alice = alice + a[i] alice 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) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];

		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
		}
		int alice = 0;
		int bob = 0;
		Arrays.sort(a);
		for (int i = n - 1; i >= 0; i--) {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				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();
		int a[] = new int[n];

		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
		}
		int alice = 0;
		int bob = 0;
		Arrays.sort(a);
		for (int i = n - 1; i >= 0; i--) {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				bob += a[i];
			}
		}

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

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];

		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
		}
		int alice = 0;
		int bob = 0;
		Arrays.sort(a);
		for (int i = n - 1; i >= 0; i--) {
			if (i % 2 == (n - 1) % 2) {
				alice = alice + a[i];
			} else {
				bob += a[i];
			}
		}

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