import java.util.*;

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

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