import java.util.*;
class Main{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        int n=Integer.parseInt(sc.next());
        Integer A[]=new Integer[n];
        for (int i=0;i<n;i++){
            A[i]=Integer.parseInt(sc.next());
        }
        Arrays.sort(A,Comparator.reverseOrder());
        int Alice=0;
        int Bob  =0;
        for (int i=0;i<n;i+=2){
            Alice+=A[i];
        }
        for (int i=1;i<n;i+=2){
            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