import java.util.Scanner;
import java.util.Arrays;
import java.util.Comparator;
 
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    Integer a[] = new Integer[N];
    for(int i=0;i<N;i++){
      a[i] = sc.nextInt();
    }
    Arrays.sort(a,Comparator.reverseOrder());
    
    int Alice = 0;
    int Bob = 0;
    for(int i=0;i<N;i+=2){
      Alice += a[i];
    }
    for(int i=1;i<N;i+=2){
      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[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    Integer a[] = new Integer[N];
    for(int i=0;i<N;i++){
      a[i] = sc.nextInt();
    }
    Arrays.sort(a,Comparator.reverseOrder());
    
    int Alice = 0;
    int Bob = 0;
    for(int i=0;i<N;i+=2){
      Alice += a[i];
    }
    for(int i=1;i<N;i+=2){
      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();
    Integer a[] = new Integer[N];
    for(int i=0;i<N;i++){
      a[i] = sc.nextInt();
    }
    Arrays.sort(a,Comparator.reverseOrder());
    
    int Alice = 0;
    int Bob = 0;
    for(int i=0;i<N;i+=2){
      Alice += a[i];
    }
    for(int i=1;i<N;i+=2){
      Bob += a[i];
    }
    
    System.out.println(Alice-Bob);
  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    Integer a[] = new Integer[N];
    for(int i=0;i<N;i++){
      a[i] = sc.nextInt();
    }
    Arrays.sort(a,Comparator.reverseOrder());
    
    int Alice = 0;
    int Bob = 0;
    for(int i=0;i<N;i+=2){
      Alice += a[i];
    }
    for(int i=1;i<N;i+=2){
      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 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,Comparator.reverseOrder()) Arrays.sort Arrays a Comparator.reverseOrder() Comparator.reverseOrder Comparator int Alice = 0; Alice 0 int Bob = 0; Bob 0 for(int i=0;i<N;i+=2){
      Alice += a[i];
    } int i=0; int i=0; i 0 i<N i N i+=2 i+=2 i 2 {
      Alice += a[i];
    } {
      Alice += a[i];
    } Alice += a[i] Alice a[i] a i for(int i=1;i<N;i+=2){
      Bob += a[i];
    } int i=1; int i=1; i 1 i<N i N i+=2 i+=2 i 2 {
      Bob += 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
import java.util.Scanner;
import java.util.Arrays;
import java.util.Comparator;
 
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    Integer a[] = new Integer[N];
    for(int i=0;i<N;i++){
      a[i] = sc.nextInt();
    }
    Arrays.sort(a,Comparator.reverseOrder());
    
    int Alice = 0;
    int Bob = 0;
    for(int i=0;i<N;i+=2){
      Alice += a[i];
    }
    for(int i=1;i<N;i+=2){
      Bob += a[i];
    }
    
    System.out.println(Alice-Bob);
  }
}