import java.util.*;
 
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    List<Integer> list = new ArrayList<Integer>();
    int num = sc.nextInt();
    
    while(sc.hasNext()){
      list.add(sc.nextInt());
    }
    Collections.sort(list,  Collections.reverseOrder());
    //System.out.println(list);
      
    int alisNum = 0;
    int bobNum = 0;
    for(int i = 0; i < num; i++){
    	if(i % 2 == 0){
        	alisNum += list.get(i);
          	//System.out.println(alisNum);
        } else {
          	bobNum += list.get(i);
            //System.out.println(bobNum);
        }  
    }  
    System.out.println(alisNum-bobNum);
  }
}
/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