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];
    boolean isAlice = true;
    int alice =0;
    int bob = 0;
    for(int i=0;i<N;i++){
      a[i]=sc.nextInt();
    }
    Arrays.sort(a);
    for(int i=0;i<N;i++){
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    }
    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];
    boolean isAlice = true;
    int alice =0;
    int bob = 0;
    for(int i=0;i<N;i++){
      a[i]=sc.nextInt();
    }
    Arrays.sort(a);
    for(int i=0;i<N;i++){
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    }
    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];
    boolean isAlice = true;
    int alice =0;
    int bob = 0;
    for(int i=0;i<N;i++){
      a[i]=sc.nextInt();
    }
    Arrays.sort(a);
    for(int i=0;i<N;i++){
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    }
    System.out.println(alice-bob);
  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int a[] = new int[N];
    boolean isAlice = true;
    int alice =0;
    int bob = 0;
    for(int i=0;i<N;i++){
      a[i]=sc.nextInt();
    }
    Arrays.sort(a);
    for(int i=0;i<N;i++){
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    }
    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 boolean isAlice = true; isAlice true 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) Arrays.sort Arrays a for(int i=0;i<N;i++){
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    } int i=0; int i=0; i 0 i<N i N i++ i++ i {
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    } {
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    } if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      } isAlice {
        alice=alice+a[N-1-i];
      } alice=alice+a[N-1-i] alice alice+a[N-1-i] alice a[N-1-i] a N-1-i N-1-i N 1 i {
        bob=bob+a[N-1-i];
      } bob=bob+a[N-1-i] bob bob+a[N-1-i] bob a[N-1-i] a N-1-i N-1-i N 1 i isAlice=!isAlice isAlice !isAlice isAlice 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];
    boolean isAlice = true;
    int alice =0;
    int bob = 0;
    for(int i=0;i<N;i++){
      a[i]=sc.nextInt();
    }
    Arrays.sort(a);
    for(int i=0;i<N;i++){
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    }
    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];
    boolean isAlice = true;
    int alice =0;
    int bob = 0;
    for(int i=0;i<N;i++){
      a[i]=sc.nextInt();
    }
    Arrays.sort(a);
    for(int i=0;i<N;i++){
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    }
    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];
    boolean isAlice = true;
    int alice =0;
    int bob = 0;
    for(int i=0;i<N;i++){
      a[i]=sc.nextInt();
    }
    Arrays.sort(a);
    for(int i=0;i<N;i++){
      if(isAlice){
        alice=alice+a[N-1-i];
      }else{
        bob=bob+a[N-1-i];
      }
      isAlice=!isAlice;
    }
    System.out.println(alice-bob);
  }
  

  
}