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];
        for(int i = 0; i < n; i++){
            a[i] = sc.nextInt();
        }
        Arrays.sort(a);
        int alice = 0;
        int bob = 0;
        for(int i = 0; i <= n-1; i++){
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        }
        System.out.print(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