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

class Main{
	public static void main(String arg[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		sc.nextLine();
		Integer[]a = new Integer[N];
		int ans = 0;
		int Alice = 0;
		int Bob = 0;
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		sc.close();
		
		Arrays.sort(a, Comparator.reverseOrder());
		
		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.Scanner; Scanner java.util import java.util.Arrays; Arrays java.util import java.util.Comparator; Comparator java.util class Main{
	public static void main(String arg[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		sc.nextLine();
		Integer[]a = new Integer[N];
		int ans = 0;
		int Alice = 0;
		int Bob = 0;
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		sc.close();
		
		Arrays.sort(a, Comparator.reverseOrder());
		
		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 arg[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		sc.nextLine();
		Integer[]a = new Integer[N];
		int ans = 0;
		int Alice = 0;
		int Bob = 0;
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		sc.close();
		
		Arrays.sort(a, Comparator.reverseOrder());
		
		for(int i = 0; i < N; i++) {
			if( i % 2 == 0 ) {
				Alice += a[i];
			}else {
				Bob += a[i];
			}
		}
		System.out.println(Alice - Bob);
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		sc.nextLine();
		Integer[]a = new Integer[N];
		int ans = 0;
		int Alice = 0;
		int Bob = 0;
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		sc.close();
		
		Arrays.sort(a, Comparator.reverseOrder());
		
		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); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc sc.nextLine() sc.nextLine sc Integer[]a = new Integer[N]; a new Integer[N] N int ans = 0; ans 0 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 sc.close() sc.close sc Arrays.sort(a, Comparator.reverseOrder()) Arrays.sort Arrays a Comparator.reverseOrder() Comparator.reverseOrder Comparator 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 arg[] arg
import java.util.Scanner;
import java.util.Arrays;
import java.util.Comparator;

class Main{
	public static void main(String arg[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		sc.nextLine();
		Integer[]a = new Integer[N];
		int ans = 0;
		int Alice = 0;
		int Bob = 0;
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		sc.close();
		
		Arrays.sort(a, Comparator.reverseOrder());
		
		for(int i = 0; i < N; i++) {
			if( i % 2 == 0 ) {
				Alice += a[i];
			}else {
				Bob += a[i];
			}
		}
		System.out.println(Alice - Bob);
	}
}