import java.util.*;

//くそコード
class Main{
  public static void main(String[] args){
    try(Scanner sc = new Scanner(System.in)){
      int n = Integer.parseInt(sc.nextLine());
      //int a[] = new int[n];
      Integer a[] = new Integer[n];
      for(int i = 0; i < n; i++){
        a[i] = Integer.parseInt(sc.next());
      }
      int Alice = 0;
      int Bob = 0;
      Arrays.sort(a, Collections.reverseOrder());
      
      for(int i = 0; i < n; i++){
        if((i % 2) == 0){
          Alice = Alice + a[i];
        }else{
          Bob = 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