import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        int alice = 0;
        int bob = 0;
        for (int i =0;i<n;i++){
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[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