import java.util.Scanner;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int number = sc.nextInt();
    int[] cardList = new int[number];
    int scoreA = 0;
    int scoreB = 0;
    for(int i =0; i < number; i++){
     	cardList[i] = sc.nextInt(); //カード情報の格納
    }
    for(int i = 0; i < number; i++){ //お互いに最大値のカードを取る
      int maxCard = cardList[0];
      int position = 0; //最大値の位置
      for(int j = 1; j < number; j++){
          if(cardList[j] > maxCard){
            maxCard = cardList[j];
            position = j;
          }
      }
      cardList[position] = 0; //最大値の消去
      if( i % 2 == 0) scoreA += maxCard;
      else scoreB += maxCard;
    }
    System.out.println(scoreA - scoreB);
    
  }
}
/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