import java.util.*;
class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int ans=0;
    int n=sc.nextInt();
    int[] nums=new int[n];
    for(int i=0;i<n;i++){
      nums[i]=sc.nextInt();
    }
    Arrays.sort(nums);
    for(int i=0;i<n;i++){
      ans+=nums[n-1-i]*(i%2==0?1:-1);
    }
    System.out.println(ans);
  }
} import java.util.*; util.* java class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int ans=0;
    int n=sc.nextInt();
    int[] nums=new int[n];
    for(int i=0;i<n;i++){
      nums[i]=sc.nextInt();
    }
    Arrays.sort(nums);
    for(int i=0;i<n;i++){
      ans+=nums[n-1-i]*(i%2==0?1:-1);
    }
    System.out.println(ans);
  }
} Main public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int ans=0;
    int n=sc.nextInt();
    int[] nums=new int[n];
    for(int i=0;i<n;i++){
      nums[i]=sc.nextInt();
    }
    Arrays.sort(nums);
    for(int i=0;i<n;i++){
      ans+=nums[n-1-i]*(i%2==0?1:-1);
    }
    System.out.println(ans);
  } main {
    Scanner sc=new Scanner(System.in);
    int ans=0;
    int n=sc.nextInt();
    int[] nums=new int[n];
    for(int i=0;i<n;i++){
      nums[i]=sc.nextInt();
    }
    Arrays.sort(nums);
    for(int i=0;i<n;i++){
      ans+=nums[n-1-i]*(i%2==0?1:-1);
    }
    System.out.println(ans);
  } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int ans=0; ans 0 int n=sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] nums=new int[n]; nums new int[n] n for(int i=0;i<n;i++){
      nums[i]=sc.nextInt();
    } int i=0; int i=0; i 0 i<n i n i++ i++ i {
      nums[i]=sc.nextInt();
    } {
      nums[i]=sc.nextInt();
    } nums[i]=sc.nextInt() nums[i] nums i sc.nextInt() sc.nextInt sc Arrays.sort(nums) Arrays.sort Arrays nums for(int i=0;i<n;i++){
      ans+=nums[n-1-i]*(i%2==0?1:-1);
    } int i=0; int i=0; i 0 i<n i n i++ i++ i {
      ans+=nums[n-1-i]*(i%2==0?1:-1);
    } {
      ans+=nums[n-1-i]*(i%2==0?1:-1);
    } ans+=nums[n-1-i]*(i%2==0?1:-1) ans nums[n-1-i]*(i%2==0?1:-1) nums[n-1-i] nums n-1-i n-1-i n 1 i (i%2==0?1:-1) i%2==0 i%2 i 2 0 1 -1 1 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 ans=0;
    int n=sc.nextInt();
    int[] nums=new int[n];
    for(int i=0;i<n;i++){
      nums[i]=sc.nextInt();
    }
    Arrays.sort(nums);
    for(int i=0;i<n;i++){
      ans+=nums[n-1-i]*(i%2==0?1:-1);
    }
    System.out.println(ans);
  }
}