import java.util.*;
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = Integer.parseInt(sc.next());
    int[] a = new int[n];
    for (int i = 0; i < n; i++){
      a[i] = Integer.parseInt(sc.next());
    }
    Arrays.sort(a);
    int ans = 0;
    boolean flag = true;
    for (int i = n-1; i >= 0; i--){
      if (flag == true){ans += a[i];}
      else{ans -= a[i];}
      flag ^= true;
    }
    System.out.println(ans);
  }
} import java.util.*; util.* java class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = Integer.parseInt(sc.next());
    int[] a = new int[n];
    for (int i = 0; i < n; i++){
      a[i] = Integer.parseInt(sc.next());
    }
    Arrays.sort(a);
    int ans = 0;
    boolean flag = true;
    for (int i = n-1; i >= 0; i--){
      if (flag == true){ans += a[i];}
      else{ans -= a[i];}
      flag ^= true;
    }
    System.out.println(ans);
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = Integer.parseInt(sc.next());
    int[] a = new int[n];
    for (int i = 0; i < n; i++){
      a[i] = Integer.parseInt(sc.next());
    }
    Arrays.sort(a);
    int ans = 0;
    boolean flag = true;
    for (int i = n-1; i >= 0; i--){
      if (flag == true){ans += a[i];}
      else{ans -= a[i];}
      flag ^= true;
    }
    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);
    int n = Integer.parseInt(sc.next());
    int[] a = new int[n];
    for (int i = 0; i < n; i++){
      a[i] = Integer.parseInt(sc.next());
    }
    Arrays.sort(a);
    int ans = 0;
    boolean flag = true;
    for (int i = n-1; i >= 0; i--){
      if (flag == true){ans += a[i];}
      else{ans -= a[i];}
      flag ^= true;
    }
    System.out.println(ans);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = Integer.parseInt(sc.next()); n Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int[] a = new int[n]; a new int[n] n for (int i = 0; i < n; i++){
      a[i] = Integer.parseInt(sc.next());
    } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
      a[i] = Integer.parseInt(sc.next());
    } {
      a[i] = Integer.parseInt(sc.next());
    } a[i] = Integer.parseInt(sc.next()) a[i] a i Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc Arrays.sort(a) Arrays.sort Arrays a int ans = 0; ans 0 boolean flag = true; flag true for (int i = n-1; i >= 0; i--){
      if (flag == true){ans += a[i];}
      else{ans -= a[i];}
      flag ^= true;
    } int i = n-1; int i = n-1; i n-1 n 1 i >= 0 i 0 i-- i-- i {
      if (flag == true){ans += a[i];}
      else{ans -= a[i];}
      flag ^= true;
    } {
      if (flag == true){ans += a[i];}
      else{ans -= a[i];}
      flag ^= true;
    } if (flag == true){ans += a[i];}
      else{ans -= a[i];} flag == true flag true {ans += a[i];} ans += a[i] ans a[i] a i {ans -= a[i];} ans -= a[i] ans a[i] a i flag ^= true flag true System.out.println(ans) System.out.println System.out System System.out ans String[] args args
import java.util.*;
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = Integer.parseInt(sc.next());
    int[] a = new int[n];
    for (int i = 0; i < n; i++){
      a[i] = Integer.parseInt(sc.next());
    }
    Arrays.sort(a);
    int ans = 0;
    boolean flag = true;
    for (int i = n-1; i >= 0; i--){
      if (flag == true){ans += a[i];}
      else{ans -= a[i];}
      flag ^= true;
    }
    System.out.println(ans);
  }
}