import 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++) {
      if (i % 2 == 0) {
        alice += a[i];
      } else {
        bob += a[i];
      }
    }
    System.out.println(alice - bob);
  }
} import java.util.*; util.* java 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++) {
      if (i % 2 == 0) {
        alice += a[i];
      } else {
        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++) {
      if (i % 2 == 0) {
        alice += a[i];
      } else {
        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++) {
      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 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++) {
      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
import 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++) {
      if (i % 2 == 0) {
        alice += a[i];
      } else {
        bob += a[i];
      }
    }
    System.out.println(alice - bob);
  }
}