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];
	int x= 0;
	int y= 0;

	for(int i=0;i<n;i++) {
		a[i]  = sc.nextInt();
	}
	Arrays.sort(a, Collections.reverseOrder());
	try{
	for(int i=0;i<n;i+=2) {
		x += a[i];
	}
	for(int i=1;i<n;i+=2) {
		y += a[i];
	}
	}catch(Exception e) {

	}
	System.out.println(x-y);
	}
} 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];
	int x= 0;
	int y= 0;

	for(int i=0;i<n;i++) {
		a[i]  = sc.nextInt();
	}
	Arrays.sort(a, Collections.reverseOrder());
	try{
	for(int i=0;i<n;i+=2) {
		x += a[i];
	}
	for(int i=1;i<n;i+=2) {
		y += a[i];
	}
	}catch(Exception e) {

	}
	System.out.println(x-y);
	}
} Main public static void main(String[] args){
	Scanner sc=new Scanner(System.in);
	int n=sc.nextInt();
	Integer a[] = new Integer[n];
	int x= 0;
	int y= 0;

	for(int i=0;i<n;i++) {
		a[i]  = sc.nextInt();
	}
	Arrays.sort(a, Collections.reverseOrder());
	try{
	for(int i=0;i<n;i+=2) {
		x += a[i];
	}
	for(int i=1;i<n;i+=2) {
		y += a[i];
	}
	}catch(Exception e) {

	}
	System.out.println(x-y);
	} main {
	Scanner sc=new Scanner(System.in);
	int n=sc.nextInt();
	Integer a[] = new Integer[n];
	int x= 0;
	int y= 0;

	for(int i=0;i<n;i++) {
		a[i]  = sc.nextInt();
	}
	Arrays.sort(a, Collections.reverseOrder());
	try{
	for(int i=0;i<n;i+=2) {
		x += a[i];
	}
	for(int i=1;i<n;i+=2) {
		y += a[i];
	}
	}catch(Exception e) {

	}
	System.out.println(x-y);
	} 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 int x= 0; x 0 int y= 0; y 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, Collections.reverseOrder()) Arrays.sort Arrays a Collections.reverseOrder() Collections.reverseOrder Collections try{
	for(int i=0;i<n;i+=2) {
		x += a[i];
	}
	for(int i=1;i<n;i+=2) {
		y += a[i];
	}
	}catch(Exception e) {

	} catch(Exception e) {

	} Exception e {

	} {
	for(int i=0;i<n;i+=2) {
		x += a[i];
	}
	for(int i=1;i<n;i+=2) {
		y += a[i];
	}
	} for(int i=0;i<n;i+=2) {
		x += a[i];
	} int i=0; int i=0; i 0 i<n i n i+=2 i+=2 i 2 {
		x += a[i];
	} {
		x += a[i];
	} x += a[i] x a[i] a i for(int i=1;i<n;i+=2) {
		y += a[i];
	} int i=1; int i=1; i 1 i<n i n i+=2 i+=2 i 2 {
		y += a[i];
	} {
		y += a[i];
	} y += a[i] y a[i] a i System.out.println(x-y) System.out.println System.out System System.out x-y x y 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];
	int x= 0;
	int y= 0;

	for(int i=0;i<n;i++) {
		a[i]  = sc.nextInt();
	}
	Arrays.sort(a, Collections.reverseOrder());
	try{
	for(int i=0;i<n;i+=2) {
		x += a[i];
	}
	for(int i=1;i<n;i+=2) {
		y += a[i];
	}
	}catch(Exception e) {

	}
	System.out.println(x-y);
	}
} public class Main{
	public static void main(String[] args){
	Scanner sc=new Scanner(System.in);
	int n=sc.nextInt();
	Integer a[] = new Integer[n];
	int x= 0;
	int y= 0;

	for(int i=0;i<n;i++) {
		a[i]  = sc.nextInt();
	}
	Arrays.sort(a, Collections.reverseOrder());
	try{
	for(int i=0;i<n;i+=2) {
		x += a[i];
	}
	for(int i=1;i<n;i+=2) {
		y += a[i];
	}
	}catch(Exception e) {

	}
	System.out.println(x-y);
	}
} 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];
	int x= 0;
	int y= 0;

	for(int i=0;i<n;i++) {
		a[i]  = sc.nextInt();
	}
	Arrays.sort(a, Collections.reverseOrder());
	try{
	for(int i=0;i<n;i+=2) {
		x += a[i];
	}
	for(int i=1;i<n;i+=2) {
		y += a[i];
	}
	}catch(Exception e) {

	}
	System.out.println(x-y);
	}
}