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];
    int alice =0,bob=0;
    for (int i=0; i<N; i++) {
      a[i] = sc.nextInt();
    }
    Arrays.sort(a);
    for (int i=0; i<=(N-1)/2; i++) {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    }
    for (int i=0; i<=N-1; i++) {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) 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];
    int alice =0,bob=0;
    for (int i=0; i<N; i++) {
      a[i] = sc.nextInt();
    }
    Arrays.sort(a);
    for (int i=0; i<=(N-1)/2; i++) {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    }
    for (int i=0; i<=N-1; i++) {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) 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];
    int alice =0,bob=0;
    for (int i=0; i<N; i++) {
      a[i] = sc.nextInt();
    }
    Arrays.sort(a);
    for (int i=0; i<=(N-1)/2; i++) {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    }
    for (int i=0; i<=N-1; i++) {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) bob += a[i];
    }
    System.out.println(alice - bob);
  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int a[] = new int[N];
    int alice =0,bob=0;
    for (int i=0; i<N; i++) {
      a[i] = sc.nextInt();
    }
    Arrays.sort(a);
    for (int i=0; i<=(N-1)/2; i++) {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    }
    for (int i=0; i<=N-1; i++) {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) 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 int alice =0 alice 0 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-1)/2; i++) {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    } int i=0; int i=0; i 0 i<=(N-1)/2 i (N-1)/2 (N-1) N 1 2 i++ i++ i {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    } {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    } int tmp = a[i]; tmp a[i] a i a[i] = a[N-1-i] a[i] a i a[N-1-i] a N-1-i N-1-i N 1 i a[N-1-i] = tmp a[N-1-i] a N-1-i N-1-i N 1 i tmp for (int i=0; i<=N-1; i++) {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) bob += a[i];
    } int i=0; int i=0; i 0 i<=N-1 i N-1 N 1 i++ i++ i {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) bob += a[i];
    } {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) bob += a[i];
    } if(i % 2 ==0) alice += a[i]; i % 2 ==0 i % 2 i 2 0 alice += a[i] alice a[i] a i if(i % 2 ==1) bob += a[i]; i % 2 ==1 i % 2 i 2 1 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];
    int alice =0,bob=0;
    for (int i=0; i<N; i++) {
      a[i] = sc.nextInt();
    }
    Arrays.sort(a);
    for (int i=0; i<=(N-1)/2; i++) {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    }
    for (int i=0; i<=N-1; i++) {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) 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];
    int alice =0,bob=0;
    for (int i=0; i<N; i++) {
      a[i] = sc.nextInt();
    }
    Arrays.sort(a);
    for (int i=0; i<=(N-1)/2; i++) {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    }
    for (int i=0; i<=N-1; i++) {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) 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];
    int alice =0,bob=0;
    for (int i=0; i<N; i++) {
      a[i] = sc.nextInt();
    }
    Arrays.sort(a);
    for (int i=0; i<=(N-1)/2; i++) {
      int tmp = a[i];
      a[i] = a[N-1-i];
      a[N-1-i] = tmp;
    }
    for (int i=0; i<=N-1; i++) {
      if(i % 2 ==0) alice += a[i];
      if(i % 2 ==1) bob += a[i];
    }
    System.out.println(alice - bob);
  }
}