import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] array = new int[n];
        for(int i = 0 ; i < n ; i ++){
          array[i] = sc.nextInt();
        }
      	Arrays.sort(array);
        int a = 0 ;
        int b = 0 ;
      	
      	for(int i = 1 ; i <= n ; i ++){
          if(i % 2 != 0){
          	a += array[n-i];
          }else{
          	b += array[n-i];
          }
        }
       System.out.print(a-b);
      
    }
}



/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