import java.util.Scanner;
import java.util.Arrays;
class Main{
    public static void main(String[] args) {
        Scanner scn= new Scanner(System.in);
        int n=scn.nextInt();
        int[] a= new int[n];
        for(int i=0;i<n;i++){
            a[i]=scn.nextInt();
        }
        Arrays.sort(a);
        int alice=0;
        int bob=0;
        for(int i=0;i<n;i++){
            if(n%2==0){
                if(i%2==0){
                    bob+=a[i];
                }else{
                    alice+=a[i];
                }
            }else{
                if(i%2==0){
                    alice+=a[i];
                }else{
                    bob+=a[i];
                }
            }
        }
        System.out.println(alice-bob);
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz