import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        Integer [] list = new Integer[num];
        int Alice = 0;
        int Bob = 0;

        for(int i = 0; i < num; i++) {
            list[i] = scan.nextInt();
        }
        Arrays.sort(list, Collections.reverseOrder());
        for(int i = 0; i < num; i++){
            if(i % 2 == 0){
                Alice += list[i];
            }
            else{
                Bob += list[i];
            }
        }
        System.out.println(Alice - Bob);
    }
}
/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