import java.util.*;
public class Main{
	public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
      int n = sc.nextInt();
      int[] a = new int[n];
      int x = 0;
      int y = 0;
      for(int i = 0;i < n;i++){
        a[i] = sc.nextInt();
        y += a[i];
      }
      Arrays.sort(a);
      for(int i = n-1;i>=0;i -= 2){
      	x += a[i];
      }
      System.out.println(x*2-y);
    }
}
/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