import java.util.*;

public class Main {
    public static void main(String[] args){
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        Integer[] a = new Integer[N];
        
        int Alice = 0;
        int Bob = 0;
        
        for(int i = 0; i < N; i++){
            a[i] = sc.nextInt();
        }
        Arrays.sort(a, Collections.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.*; util.* java public class Main {
    public static void main(String[] args){
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        Integer[] a = new Integer[N];
        
        int Alice = 0;
        int Bob = 0;
        
        for(int i = 0; i < N; i++){
            a[i] = sc.nextInt();
        }
        Arrays.sort(a, Collections.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[] args){
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        Integer[] a = new Integer[N];
        
        int Alice = 0;
        int Bob = 0;
        
        for(int i = 0; i < N; i++){
            a[i] = sc.nextInt();
        }
        Arrays.sort(a, Collections.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 {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        Integer[] a = new Integer[N];
        
        int Alice = 0;
        int Bob = 0;
        
        for(int i = 0; i < N; i++){
            a[i] = sc.nextInt();
        }
        Arrays.sort(a, Collections.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 Integer[] a = new Integer[N]; a new Integer[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, Collections.reverseOrder()) Arrays.sort Arrays a Collections.reverseOrder() Collections.reverseOrder Collections 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[] args args public class Main {
    public static void main(String[] args){
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        Integer[] a = new Integer[N];
        
        int Alice = 0;
        int Bob = 0;
        
        for(int i = 0; i < N; i++){
            a[i] = sc.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        
        for(int i = 0; i < N; i++){
            if((i % 2) == 0 ){
                Alice += a[i];
            }else{
                Bob += a[i];
            }
        }
        
        System.out.println(Alice - Bob);
    }
    
} public class Main {
    public static void main(String[] args){
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        Integer[] a = new Integer[N];
        
        int Alice = 0;
        int Bob = 0;
        
        for(int i = 0; i < N; i++){
            a[i] = sc.nextInt();
        }
        Arrays.sort(a, Collections.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
import java.util.*;

public class Main {
    public static void main(String[] args){
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        Integer[] a = new Integer[N];
        
        int Alice = 0;
        int Bob = 0;
        
        for(int i = 0; i < N; i++){
            a[i] = sc.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        
        for(int i = 0; i < N; i++){
            if((i % 2) == 0 ){
                Alice += a[i];
            }else{
                Bob += a[i];
            }
        }
        
        System.out.println(Alice - Bob);
    }
    
}
