import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

public class Main {

    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);
        final int n = Integer.valueOf(sc.next());
        Integer[] ai = new Integer[n];
        for(int i=0; i<n; i++){
            ai[i] = sc.nextInt();
        }
        Arrays.sort(ai ,Comparator.reverseOrder());
        int alice = 0;
        int bob = 0;
        for(int i=0; i < ai.length; i=i+2) {
            alice += ai[i];
        }
        for(int j=1; j< ai.length; j=j+2) {
            bob += ai[j];
        }
        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