import java.util.Arrays;
import java.util.Scanner;
     
    public class Main {
      public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int []a = new int[N];
        
        int A = 0;
        int B = 0;
        for(int i=0; i<N; i++) {
        	 a[i] = sc.nextInt();
        }
        Arrays.sort(a);
        for(int i=0; i<N; i++) {
        	if(i%2 != 0) {
        		A += a[i];
        	}else {
        		B += a[i];
        	}
        }
        System.out.println(Math.abs(A-B));
      }
    }
/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