

import java.io.IOException;
import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		int a[] = new int[n];
		int alice = 0;
		int bob = 0;

		for(int i = 0; i < n; i++){
			a[i] = sc.nextInt();
		}

		Arrays.sort(a);

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

		System.out.println(alice - bob);
	}
} import java.io.IOException; IOException java.io import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		int a[] = new int[n];
		int alice = 0;
		int bob = 0;

		for(int i = 0; i < n; i++){
			a[i] = sc.nextInt();
		}

		Arrays.sort(a);

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

		System.out.println(alice - bob);
	}
} Main public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		int a[] = new int[n];
		int alice = 0;
		int bob = 0;

		for(int i = 0; i < n; i++){
			a[i] = sc.nextInt();
		}

		Arrays.sort(a);

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

		System.out.println(alice - bob);
	} main {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		int a[] = new int[n];
		int alice = 0;
		int bob = 0;

		for(int i = 0; i < n; i++){
			a[i] = sc.nextInt();
		}

		Arrays.sort(a);

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

		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 int alice = 0; alice 0 int bob = 0; bob 0 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) Arrays.sort Arrays a for(int i = 0; i < n; i++){
			if(i % 2 == 0){
				alice += a[n - i - 1];
			}
			else {
				bob += a[n - i - 1];
			}
		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
			if(i % 2 == 0){
				alice += a[n - i - 1];
			}
			else {
				bob += a[n - i - 1];
			}
		} {
			if(i % 2 == 0){
				alice += a[n - i - 1];
			}
			else {
				bob += a[n - i - 1];
			}
		} if(i % 2 == 0){
				alice += a[n - i - 1];
			}
			else {
				bob += a[n - i - 1];
			} i % 2 == 0 i % 2 i 2 0 {
				alice += a[n - i - 1];
			} alice += a[n - i - 1] alice a[n - i - 1] a n - i - 1 n - i - 1 n i 1 {
				bob += a[n - i - 1];
			} bob += a[n - i - 1] bob a[n - i - 1] a n - i - 1 n - i - 1 n i 1 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) throws IOException {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		int a[] = new int[n];
		int alice = 0;
		int bob = 0;

		for(int i = 0; i < n; i++){
			a[i] = sc.nextInt();
		}

		Arrays.sort(a);

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

		System.out.println(alice - bob);
	}
} public class Main {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		int a[] = new int[n];
		int alice = 0;
		int bob = 0;

		for(int i = 0; i < n; i++){
			a[i] = sc.nextInt();
		}

		Arrays.sort(a);

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

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


import java.io.IOException;
import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		int a[] = new int[n];
		int alice = 0;
		int bob = 0;

		for(int i = 0; i < n; i++){
			a[i] = sc.nextInt();
		}

		Arrays.sort(a);

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

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