import static java.util.Arrays.sort;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int scoreCard[] = new int[N];
        
        for(int i = 0; i < N; i++){
            scoreCard[i] = sc.nextInt();
        //    System.out.println(scoreCard[i]);
        }
        
        sort(scoreCard);
        /*
        for(int num : scoreCard){
            System.out.println(num);
        }
        */
        int Alice = 0, Bob = 0;
        boolean flg = true;
        for(int i = scoreCard.length -1; i >= 0; i--){
            if(flg){
                Alice += scoreCard[i];
        //        System.out.println("A" + Alice);
                flg = false;
            }else{
                Bob += scoreCard[i];
        //        System.out.println("B" + Bob);
                flg = true;
            }
        }
        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