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();
   
   int allsum = 0;
   int sumA = 0;
   
   Arrays.sort(a);
   for(int i=0;i<N;i++) allsum+=a[i];
   if(N%2==1)
   {
     for(int i=0;i<N;i+=2) sumA+=a[i];
   }
   else   
   {
     for(int i=1;i<N;i+=2) sumA+=a[i];
   }
   
   System.out.println(2*sumA-allsum);
 }
}
/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