import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        
        int result = 0;
        
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Integer card[] = new Integer[n];
        
        for (int i=0; i < n; i++){
            card[i] = sc.nextInt();
        }
            
        Arrays.sort(card,Collections.reverseOrder());
        
        int alice = 0;
        int bob = 0;
        
        for (int i=0; i < n; i++){
            if (i % 2 == 0){
                alice += card[i];
            } else{
                bob += card[i];
            }
        }
        
        System.out.println(alice - bob);
        sc.close();
    }
}

/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